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<h2> CHAPTER XII. MATHEMATICAL MEMORIES: NEWTON'S BINOMIAL THEOREM </h2>
<p>The spider's web is a glorious mathematical problem. I should enjoy
working it out in all its details, were I not afraid of wearying the
reader's attention. Perhaps I have even gone too far in the little that I
have said, in which case I owe him some compensation: 'Would you like me,'
I will ask him, 'would you like me to tell you how I acquired sufficient
algebra to master the logarithmic systems and how I became a surveyor of
Spiders' webs? Would you? It will give us a rest from natural history.'</p>
<p>I seem to catch a sign of acquiescence. The story of my village school,
visited by the chicks and the porkers, has been received with some
indulgence; why should not my harsh school of solitude possess its
interest as well? Let us try to describe it. And who knows? Perhaps, in
doing so, I shall revive the courage of some other poor derelict hungering
after knowledge.</p>
<p>I was denied the privilege of learning with a master. I should be wrong to
complain. Solitary study has its advantages: it does not cast you in the
official mould; it leaves you all your originality. Wild fruit, when it
ripens, has a different taste from hothouse produce: it leaves on a
discriminating palate a bittersweet flavor whose virtue is all the greater
for the contrast. Yes, if it were in my power, I would start afresh, face
to face with my only counselor, the book itself, not always a very lucid
one; I would gladly resume my lonely watches, my struggles with the
darkness whence, at last, a glimmer appears as I continue to explore it; I
should retraverse the irksome stages of yore, stimulated by the one desire
that has never failed me, the desire of learning and of afterwards
bestowing my mite of knowledge on others.</p>
<p>When I left the normal school, my stock of mathematics was of the
scantiest. How to extract a square root, how to calculate and prove the
surface of a sphere: these represented to me the culminating points of the
subject. Those terrible logarithms, when I happened to open a table of
them, made my head swim, with their columns of figures; actual fright, not
unmixed with respect, overwhelmed me on the very threshold of that
arithmetical cave. Of algebra I had no knowledge whatever. I had heard the
name; and the syllables represented to my poor brain the whole whirling
legion of the abstruse.</p>
<p>Besides, I felt no inclination to decipher the alarming hieroglyphics.
They made one of those indigestible dishes which we confidently extol
without touching them. I greatly preferred a fine line of Virgil, whom I
was now beginning to understand; and I should have been surprised indeed
had any one told me that, for long years to come, I should be an
enthusiastic student of the formidable science. Good fortune procured me
my first lesson in algebra, a lesson given and not received, of course.</p>
<p>A young man of about my own age came to me and asked me to teach him
algebra. He was preparing for his examination as a civil engineer; and he
came to me because, ingenuous youth that he was, he took me for a well of
learning. The guileless applicant was very far out in his reckoning.</p>
<p>His request gave me a shock of surprise, which was forthwith repressed on
reflection: 'I give algebra lessons?' said I to myself. 'It would be
madness: I don't know anything about the subject!'</p>
<p>And I left it at that for a moment or two, thinking hard, drawn now this
way, now that with indecision: 'Shall I accept? Shall I refuse?' continued
the inner voice.</p>
<p>Pooh, let's accept! An heroic method of learning to swim is to leap boldly
into the sea. Let us hurl ourselves head first into the algebraical gulf;
and perhaps the imminent danger of drowning will call forth efforts
capable of bringing me to land. I know nothing of what he wants. It makes
no difference: let's go ahead and plunge into the mystery. I shall learn
by teaching.</p>
<p>It was a fine courage that drove me full tilt into a province which I had
not yet thought of entering. My twenty-year-old confidence was an
incomparable lever.</p>
<p>'Very well,' I replied. 'Come the day after tomorrow, at five, and we'll
begin.'</p>
<p>This twenty-four hours' delay concealed a plan. It secured me the respite
of a day, the blessed Thursday, which would give me time to collect my
forces.</p>
<p>Thursday comes. The sky is gray and cold. In this horrid weather, a grate
well filled with coke has its charms. Let's warm ourselves and think.</p>
<p>Well, my boy, you've landed yourself in a nice predicament! How will you
manage tomorrow? With a book, plodding all through the night, if
necessary, you might scrape up something resembling a lesson, just enough
to fill the dread hour more or less. Then you could see about the next:
sufficient for the day is the evil thereof. But you haven't the book. And
it's no use running out to the bookshop. Algebraical treatises are not
current wares. You'll have to send for one, which will take a fortnight at
least. And I've promised for tomorrow, for tomorrow certain! Another
argument and one that admits of no reply: funds are low; my last pecuniary
resources lie in the corner of a drawer. I count the money: it amounts to
twelve sous, which is not enough.</p>
<p>Must I cry off? Rather not! One resource suggests itself: a highly
improper one, I admit, not far removed indeed from larceny. O quiet paths
of algebra, you are my excuse for this venial sin! Let me confess the
temporary embezzlement.</p>
<p>Life at my college is more or less cloistered. In return for a modest
payment, most of us masters are lodged in the building; and we take our
meals at the principal's table. The science master, who is the big gun of
the staff and lives in the town, has nevertheless, like ourselves, his own
two cells, in addition to a balcony, or leads, where the chemical
preparations give forth their suffocating gases in the open air. For this
reason, he finds it more convenient to hold his class here during the
greater part of the year. The boys come to these rooms in winter, in front
of a grate stuffed full of coke, like mine, and there find a blackboard, a
pneumatic trough, a mantelpiece covered with glass receivers, panoplies of
bent tubes on the walls, and, lastly, a certain cupboard in which I
remember seeing a row of books, the oracles consulted by the master in the
course of his lessons.</p>
<p>'Among those books,' said I to myself, 'there is sure to be one on
algebra. To ask the owner for the loan of it does not appeal to me. My
amiable colleague would receive me superciliously and laugh at my
ambitious aims. I am sure he would refuse my request.'</p>
<p>The future was to show that my distrust was justified. Narrow mindedness
and petty jealousy prevail everywhere alike.</p>
<p>I decide to help myself to this book, which I should never get by asking.
This is the half-holiday. The science master will not put in an appearance
today; and the key of my room is practically the same as his. I go, with
eyes and ears on the alert. My key does not quite fit; it sticks a little,
then goes in; and an extra effort makes it turn in the lock. The door
opens. I inspect the cupboard and find that it does contain an algebra
book, one of the big, fat books which men used to write in those days, a
book nearly half a foot thick. My legs give way beneath me. You poor
specimen of a housebreaker, suppose you were caught at it! However, all
goes well. Quick, let's lock the door again and go back to our own
quarters with the pilfered volume.</p>
<p>And now we are together, O mysterious tome, whose Arab name breathes a
strange mustiness of occult lore and claims kindred with the sciences of
almagest and alchemy. What will you show me? Let us turn the leaves at
random. Before fixing one's eyes on a definite point in the landscape, it
is well to take a summary view of the whole. Page follows swiftly upon
page, telling me nothing. A chapter catches my attention in the middle of
the volume; it is headed, Newton's Binomial Theorem.</p>
<p>The title allures me. What can a binomial theorem be, especially one whose
author is Newton, the great English mathematician who weighed the worlds?
What has the mechanism of the sky to do with this? Let us read and seek
for enlightenment. With my elbows on the table and my thumbs behind my
ears, I concentrate all my attention.</p>
<p>I am seized with astonishment, for I understand! There are a certain
number of letters, general symbols which are grouped in all manner of
ways, taking their places here, there and elsewhere by turns; there are,
as the text tells me, arrangements, permutations and combinations. Pen in
hand, I arrange, permute and combine. It is a very diverting exercise,
upon my word, a game in which the test of the written result confirms the
anticipations of logic and supplements the shortcomings of one's thinking
apparatus.</p>
<p>'It will be plain sailing,' said I to myself, 'if algebra is no more
difficult than this.'</p>
<p>I was to recover from the illusion later, when the binomial theorem, that
light, crisp biscuit, was followed by heavier and less digestible fare.
But, for the moment, I had no foretaste of the future difficulties, of the
pitfall in which one becomes more and more entangled, the longer one
persists in struggling. What a delightful afternoon that was, before my
grate, amid my permutations and combinations! By the evening, I had nearly
mastered my subject. When the bell rang, at seven, to summon us to the
common meal at the principal's table, I went downstairs puffed up with the
joys of the newly initiated neophyte. I was escorted on my way by a, b and
c, intertwined in cunning garlands.</p>
<p>Next day, my pupil is there. Blackboard and chalk, everything is ready.
Not quite so ready is the master. I bravely broach my binomial theorem. My
hearer becomes interested in the combinations of letters. Not for a moment
does he suspect that I am putting the cart before the horse and beginning
where we ought to have finished. I relieve the dryness of my explanations
with a few little problems, so many halts at which the mind takes breath
awhile and gathers strength for fresh flights.</p>
<p>We try together. Discreetly, so as to leave him the merit of the
discovery, I shed a little light on the path. The solution is found. My
pupil triumphs; so do I, but silently, in my inner consciousness, which
says:</p>
<p>'You understand, because you succeed in making another understand.'</p>
<p>The hour passed quickly and very pleasantly for both of us. My young man
was contented when he left me; and I no less so, for I perceived a new and
original way of learning things.</p>
<p>The ingenious and easy arrangement of the binomial gave me time to tackle
my algebra book from the proper commencement. In three or four days, I had
rubbed up my weapons. There was nothing to be said about addition and
subtraction: they were so simple as to force themselves upon one at first
sight. Multiplication spoilt things. There was a certain rule of signs
which declared that minus multiplied by minus made plus. How I toiled over
that wretched paradox! It would seem that the book did not explain this
subject clearly, or rather employed too abstract a method. I read, reread
and meditated in vain: the obscure text retained all its obscurity. That
is the drawback of books in general: they tell you what is printed in them
and nothing more. If you fail to understand, they never advise you, never
suggest an attempt along another road which might lead you to the light.
The merest word would sometimes be enough to put you on the right track;
and that word the books, hidebound in a regulation phraseology, never give
you.</p>
<p>How greatly preferable is the oral lesson! It goes forward, goes back,
starts afresh, walks around the obstacle and varies the methods of attack
until, at long last, light is shed upon the darkness. This incomparable
beacon of the master's word was what I lacked; and I went under, without
hope of succor, in that treacherous pool of the rule of signs.</p>
<p>My pupil was bound to suffer the effects. After an attempt at an
explanation in which I made the most of the few gleams that reached me I
asked him:</p>
<p>'Do you understand?'</p>
<p>It was a futile question, but useful for gaining time. Myself not
understanding, I was convinced beforehand that he did not understand
either.</p>
<p>'No,' he replied, accusing himself, perhaps, in his simple mind, of
possessing a brain incapable of taking in those transcendental verities.</p>
<p>'Let us try another method.'</p>
<p>And I start again this way and that way and yet another way. My pupil's
eyes serve as my thermometer and tell me of the progress of my efforts. A
blink of satisfaction announces my success. I have struck home, I have
found the joint in the armor. The product of minus multiplied by minus
delivers its mysteries to us.</p>
<p>And thus we continued our studies: he, the passive receiver, taking in the
ideas acquired without effort; I, the fierce pioneer, blasting my rock,
the book, with the aid of much sitting up at night, to extract the
diamond, truth. Another and no less arduous task fell to my share: I had
to cut and polish the recondite gem, to strip it of its ruggedness and
present it to my companion's intelligence under a less forbidding aspect.
This diamond cutter's work, which admitted a little light into the
precious stone, was the favorite occupation of my leisure; and I owe a
great deal to it.</p>
<p>The ultimate result was that my pupil passed his examination. As for the
book borrowed by stealth, I restored it to the shelves and replaced it by
another, which, this time, belonged to me.</p>
<p>At my normal school, I had learnt a little elementary geometry under a
master. From the first few lessons onwards, I rather enjoyed the subject.
I divined in it a guide for one's reasoning faculties through the thickets
of the imagination; I caught a glimpse of a search after truth that did
not involve too much stumbling on the way, because each step forward rests
solidly upon the step already taken; I suspected geometry to be what it
preeminently is: a school of intellectual fencing.</p>
<p>The truth demonstrated and its application matter little to me; what
rouses my enthusiasm is the process that sets the truth before us. We
start from a brilliantly lighted spot and gradually get deeper and deeper
in the darkness, which, in its turn, becomes self-illuminated by kindling
new lights for a higher ascent. This progressive march of the known toward
the unknown, this conscientious lantern lighting what follows by the rays
of what comes before: that was my real business.</p>
<p>Geometry was to teach me the logical progression of thought; it was to
tell me how the difficulties are broken up into sections which, elucidated
consecutively, together form a lever capable of moving the block that
resists any direct efforts; lastly, it showed me how order is engendered,
order, the base of clarity. If it has ever fallen to my lot to write a
page or two which the reader has run over without excessive fatigue, I owe
it, in great part, to geometry, that wonderful teacher of the art of
directing one's thought. True, it does not bestow imagination, a delicate
flower blossoming none knows how and unable to thrive on every soil; but
it arranges what is confused, thins out the dense, calms the tumultuous,
filters the muddy and gives lucidity, a superior product to all the tropes
of rhetoric.</p>
<p>Yes, as a toiler with the pen, I owe much to it. Wherefore my thoughts
readily turn back to those bright hours of my novitiate, when, retiring to
a corner of the garden in recreation time, with a bit of paper on my knees
and a stump of pencil in my fingers, I used to practice deducing this or
that property correctly from an assemblage of straight lines. The others
amused themselves all around me; I found my delight in the frustum of a
pyramid. Perhaps I should have done better to strengthen the muscles of my
thighs by jumping and leaping, to increase the suppleness of my loins with
gymnastic contortions. I have known some contortionists who have prospered
beyond the thinker.</p>
<p>See me then entering the lists as an instructor of youth, fairly well
acquainted with the elements of geometry. In case of need, I could handle
the land surveyor's stake and chain. There my views ended. To cube the
trunk of a tree, to gauge a cask, to measure the distance of an
inaccessible point appeared to me the highest pitch to which geometrical
knowledge could hope to soar. Were there loftier flights? I did not even
suspect it, when an unexpected glimpse showed me the puny dimensions of
the little corner which I had cleared in the measureless domain.</p>
<p>At that time, the college in which, two years before, I had made my first
appearance as a teacher, had just halved the size of its classes and
largely increased its staff. The newcomers all lived in the building, like
myself, and we had our meals in common at the principal's table. We formed
a hive where, in our leisure time, some of us, in our respective cells,
worked up the honey of algebra and geometry, history and physics, Greek
and Latin most of all, sometimes with a view to the class above, sometimes
and oftener with a view to acquiring a degree. The university titles
lacked variety. All my colleagues were bachelors of letters, but nothing
more. They must, if possible, arm themselves a little better to make their
way in the world. We all worked hard and steadily. I was the youngest of
the industrious community and no less eager than the rest to increase my
modest equipment.</p>
<p>Visits between the different rooms were frequent. We would come to consult
one another about a difficulty, or simply to pass the time of day. I had
as a neighbor, in the next cell to mine, a retired quartermaster who,
weary of barrack life, had taken refuge in education. When in charge of
the books of his company he had become more or less familiar with figures;
and it became his ambition to take a mathematical degree. His cerebrum
appears to have hardened while he was with his regiment. According to my
dear colleagues, those amiable retailers of the misfortunes of others, he
had already twice been plucked. Stubbornly, he returned to his books and
exercises, refusing to be daunted by two reverses.</p>
<p>It was not that he was allured by the beauties of mathematics, far from
it; but the step to which he aspired favored his plans. He hoped to have
his own boarders and dispense butter and vegetables to lucrative purpose.
The lover of study for its own sake and the persistent trapper hunting a
diploma as he would something to put in his mouth were not made to
understand or to see much of each other. Chance, however, brought us
together.</p>
<p>I had often surprised our friend sitting in the evening, by the light of a
candle, with his elbows on the table and his head between his hands,
meditating at great length in front of a big exercise book crammed with
cabalistic signs. From time to time, when an idea came to him, he would
take his pen and hastily put down a line of writing wherein letters, large
and small, were grouped without any grammatical sense. The letters x and y
often recurred, intermingled with figures. Every row ended with the sign
of equality and a nought. Next came more reflection, with closed eyes, and
a fresh row of letters arranged in a different order and likewise followed
by a nought. Page after page was filled in this queer fashion, each line
winding up with 0.</p>
<p>'What are you doing with all those rows of figures amounting to zero?' I
asked him one day.</p>
<p>The mathematician gave me a leery look, picked up in barracks. A sarcastic
droop in the corner of his eye showed how he pitied my ignorance. My
colleague of the many noughts did not, however, take an unfair advantage
of his superiority. He told me that he was working at analytical geometry.</p>
<p>The phrase had a strange effect upon me. I ruminated silently to this
purpose: there was a higher geometry, which you learnt more particularly
with combinations of letters in which x and y played a prominent part.
When my next-door neighbor reflected so long, clutching his forehead
between his hands, he was trying to discover the hidden meaning of his own
hieroglyphics; he saw the ghostly translation of his sums dancing in
space. What did he perceive? How would the alphabetical signs, arranged
first in one and then in another manner, give an image of the actual
things, an image visible to the eyes of the mind alone? It beat me.</p>
<p>'I shall have to learn analytical geometry some day,' I said. 'Will you
help me?'</p>
<p>'I'm quite willing,' he replied, with a smile in which I read his lack of
confidence in my determination.</p>
<p>No matter; we struck a bargain that same evening. We would together break
up the stubble of algebra and analytical geometry, the foundation of the
mathematical degree; we would make common stock: he would bring long hours
of calculation, I my youthful ardor. We would begin as soon as I had
finished with my arts degree, which was my main preoccupation for the
moment.</p>
<p>In those far off days it was the rule to make a little serious literary
study take precedence of science. You were expected to be familiar with
the great minds of antiquity, to converse with Horace and Virgil,
Theocritus and Plato, before touching the poisons of chemistry or the
levers of mechanics. The niceties of thought could only be the gainers by
these preparations. Life's exigencies, ever harsher as progress afflicts
us with its increasing needs, have changed all that. A fig for correct
language! Business before all!</p>
<p>This modern hurry would have suited my impatience. I confess that I fumed
against the regulation which forced Latin and Greek upon me before
allowing me to open up relations with the sine and cosine. Today, wiser,
ripened by age and experience, I am of a different opinion. I very much
regret that my modest literary studies were not more carefully conducted
and further prolonged. To fill up this enormous blank a little, I
respectfully returned, somewhat late in life, to those good old books
which are usually sold second-hand with their leaves hardly cut. Venerable
pages, annotated in pencil during the long evenings of my youth, I have
found you again and you are more than ever my friends. You have taught me
that an obligation rests upon whoever wields the pen: he must have
something to say that is capable of interesting us. When the subject comes
within the scope of natural science, the interest is nearly always
assured; the difficulty, the great difficulty, is to prune it of its
thorns and to present it under a prepossessing aspect. Truth, they say,
rises naked from a well. Agreed; but admit that she is all the better for
being decently clothed. She craves, if not the gaudy furbelows borrowed
from rhetoric's wardrobe, at least a vine leaf. The geometers alone have
the right to refuse her that modest garment; in theorems, plainness
suffices. The others, especially the naturalist, are in duty bound to
drape a gauze tunic more or less elegantly around her waist.</p>
<p>Suppose I say: 'Baptiste, give me my slippers.'</p>
<p>I am expressing myself in plain language, a little poor in variants. I
know exactly what I am saying and my speech is understood.</p>
<p>Others—and they are numerous—contend that this rudimentary
method is the best in all things. They talk science to their readers as
they might talk slippers to Baptiste. Kaffir syntax does not shock them.
Do not speak to them of the value of a well selected term, set down in its
right place, still less of a lilting construction, sounding rather well.
Childish nonsense they call all that; the fiddling of a short sighted
mind!</p>
<p>Perhaps they are right: the Baptiste idiom is a great economizer of time
and trouble. This advantage does not tempt me; it seems to me that an idea
stands out better if expressed in lucid language, with sober imagery. A
suitable phrase, placed in its correct position and saying without fuss
the things we want to say, necessitates a choice, an often laborious
choice. There are drab words, the commonplaces of colloquial speech; and
there are, so to speak, colored words, which may be compared with the
brushstrokes strewing patches of light over the gray background of a
painting. How are we to find those picturesque words, those striking
features which arrest the attention? How are we to group them into a
language heedful of syntax and not displeasing to the ear?</p>
<p>I was taught nothing of this art. For that matter, is it ever taught in
the schools? I greatly doubt it. If the fire that runs through our veins,
if inspiration do not come to our aid, we shall flutter the pages of the
thesaurus in vain: the word for which we seek will refuse to come. Then to
what masters shall we have recourse to quicken and develop the humble germ
that is latent within us? To books.</p>
<p>As a boy, I was always an ardent reader; but the niceties of a
well-balanced style hardly interested me: I did not understand them. A
good deal later, when close upon fifteen, I began vaguely to see that
words have a physiognomy of their own. Some pleased me better than others
by the distinctness of their meaning and the resonance of their rhythm;
they produced a clearer image in my mind; after their fashion, they gave
me a picture of the object described. Colored by its adjective and
vivified by its verb, the name became a living reality: what it said I
saw. And thus, gradually, was the magic of words revealed to me, when the
chances of, my undirected reading placed a few easy standard pages in my
way.</p>
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