it strikes the wall. It is no good being perfectly elastic when you strike a feather bed. It is like trying to lean up against a wall that is falling away from you, to try to rebound from a crumb going the same way as yourself. We have only to look at an india-rubber ball striking a wall, or striking the net of a tennis court, to see the difference.

But if it is better for such a ball to strike a wall than a yielding net, it is better still for it to strike a tennis racket that is coming towards it. In that case it rebounds with all its own strength, and the strength of the racket, or of the tennis-player, added as a kick behind; and the more elastic the racket is, and the harder it hits, the better for the elastic ball. I am not a very good elastician, but I am clear of this much, that when two Going Crumbs, sheathed in enchanted mail, meet each other in full career, the speed of each must be doubled by the encounter.

What is the consequence of these mathematical truths? Whenever two steady-going crumbs meet frontways there is a gain of speed for both. When one overtakes another from behind, there is a loss of speed for one, but what it loses is gained by the other. If we now consider a million crumbs as having a million pounds of speed between them, we shall see that their joint capital is not lessened by a shilling here and there being taken out of the pocket of one crumb, and put into the pocket of another; whereas the joint capital is increased whenever two crumbs endow each other with anything from a shilling upwards to a pound. Moreover the addition takes place very much oftener than the

exchange, because it takes less time for a crumb to meet another coming towards it, than to overtake one going from it.

The result of all this is that, just as real crumbs would gradually slow down and stop, and put an end to the gas in one way; so these ideal crumbs will gradually quicken their pace till they burst into flame, and put an end to the gas in another way.

That is the dilemma, and I will leave science to deal with it. In order to be understood by perfect elasticians, I will put it into shorthand: — The cumulative effect of the collision between kinetic molecules must be to equalise their average velocity, and equal average velocity must tend to produce a greater number of collisions at points of contact anterior to the molecular diameter which is at right angles to the line of direction of the molecule, than at points posterior to that diameter; so that whether such collisions accelerate or diminish the velocity of the molecule, their cumulative result must ultimately be fatal to the equilibrium of the gas.

The cryptogram, we can now see, was too fainthearted when it said that there was no loss of Energy of Motion in the encounters between the Going Crumbs. There is a gain of Energy of Motion; and it is of course that gain that produces the increasing fury of the thumps against the wall of the containing vessel. In this way we have accounted for Boyle's Law much better than the Kinetic Molecular Theory accounts for it. Indeed the only thing we have not accounted for is the Kinetic Molecule.

ELEVENTH HEAD

THE CONJURING TRICK

The Idealist Lexicon. 1. The Conjuror of Alexandria, 3. The Child's Riddle. 4. The Enchanted Castle. 5. A Work of an Idealist Tendency.

2. Pure Assurance.

Descartes likened his search for some one certain truth on which to build, to the demand of Archimedes for a fulcrum on which to swing the earth. I seek to tell what manner of book is worth a bag of gold, and what I need is one firm word that will not change into some other word, and slide and glide away.

We have now dealt with the Idealism that looks within, and the Materialism that looks without, itself. In both cases our quarrel was with words; but whereas Idealism was all words, we quarrelled with it altogether; and whereas Materialism was a mixture of facts and words, we had no quarrel with its facts. We distinguished between science and scientology.

Such differential treatment accords with the spirit of the Will we are construing, in which there are three bequests to science. If the Testator's idealism be opposed to materialism, it cannot be the mate

rialism of the laboratory, and must be the materialism of the lexicon.

Where does that opposition begin?

The last word of Materialism is not Matter, but Power. We have seen that in many ways. We have seen the demon in the falling stone, and the man in the going crumb. We have seen it still more clearly in the dissected atom, which proved to be all demon, and no crumb. The abiding mystery in the material universe is strength. Strength is, not the last word, but, verily speaking, the first word, in the scientific lexicon. It is the word that science has not explained, but by which she explains all other words. What is the first word in the idealist lexicon? What is the word that denies Strength?

I

A point is that which hath no parts, and no magnitude.

With these words began a book which was put into my hands, of course without the slightest warning of what it was about, when I was twelve years old. I need not remind any one that, like the Latin Grammar, it was a Mediterranean book, written in Mediterranean words which I only half understood.

The Romans did not write the book, any more than they wrote the Latin Grammar or the Catholic Creed. In school they were themselves Babus. Dogma streamed on Europe for two thousand years from the great lighthouse of Alexandria.

The Greeks themselves did not write the dogma; their share in it was the editing. They were vikings who ransacked the temples of buried cities and forgotten realms, and brought forth the hoards of knowledge into the marketplace. They were publishers, and Alexandria was their chief publishing house. Euclid himself was no famous geometrician, but an immortal editor. This book of his is like a hard, bright crystal imbedded in the human brain.

To me it came as literature, and I can still recall the pleasure with which I read the opening pages. I thought the ancient Alexandrian the ablest writer I had ever met with, the one who knew most surely what he wanted to say, and said it in the surest words. Those axioms, I remember, struck me as marvels of verihood; I was not awake to see that they had told me nothing but that more is more than less, and less is less than more.

I read on till I came to the place where the old conjuror, in order to show that two three-cornered figures are a pair, makes-believe to pick up one and set it down upon the other. When I saw that slice of pure flatness rise through the air before my eyes, as though it were an aeroplane, and settle down upon another slice, my mind, young as it was, boggled at the sight. The African wizard with his magic spell had cast me into a dream, and in my dream he had taken me by the sleeve and led me into a