very good reason that nobody knows. Matter is a kind of Sphinx, a sort of mental monster, challenging every philosophic passerby, every scientific question-monger, to guess its true character. The guessers have been many, from the earliest times until now, but the Sphinx, angered by their ignorance, has systematically slain them all. Thus far no Oedipus has happened along to reveal the secrets of the Sphinx of Matter. So mysterious, so unfathomable, is the problem, that thinkers are content to speak simply of the properties, or characteristics, of matter. That is all I propose doing at this juncture of my subject.

A well-known property of matter is that of position. Suppose you are on a trolley car going west at the rate of seven miles an hour. You rise in the car and walk due east exactly seven miles an hour also. Have you changed your position? Yes and no. So far as the car is concerned, you have unquestionably altered your position; so far as the earth is concerned, you have not shifted your position a hair's-breadth. Thus relativity is a big factor in thought, in life, in the universe. So matter, in the presence of the universe of spirit, has only a relative existence. This is the conclusion of all the great religions of the race.

Another characteristic of matter is motion. The physical universe, from the mightiest whirling fixed star to the minutest dancing electron, is on the move, going furiously, tremendously. Woe betide the

human passenger who complacently boards the solar train of planets and vows, in his conservative soul, that he will not budge an inch! Why, before he has had time to conceive the thought, the Great Engineer has already hurled him far onward into space. Simon Newcomb says that the greatest fact the human intellect has brought to light is this: Through all history our system has been rushing through space, at inconceivable speed, toward the constellation Lyra. Every second we are ten miles nearer that constellation, every day we are nearer it by a million miles. This has been going on since before the creation of man, and the astronomer thinks there is reason to believe that it will continue to our remotest posterity. But when our system has reached the position in space now occupied by Vega, the most brilliant star in the constellation Lyra, think you that we shall have overtaken our stellar quarry? By no means! They will have rushed onward into space just as far in advance of our panting, exhausted, pursuing solar system as they are at present. In view of the fact, then, that all matter, whatever it is, is in ceaseless motion, let me ask you this question: Has the house in which you live moved during the last ten years, or even in the past six months? Again-yes and no. With reference to the houses on either side of it, your house has not perceptibly moved; but just how far your house has moved with reference to the Earth, Mercury, Venus, Jupiter, the Sun, and

the fixed stars, which are anything but "fixed," I would not dare to say. But I will venture this: If your house, in common with all matter-your physical body included—has not moved 365,000,000 miles in the last twelvemonth, and 72,000 miles in the last two hours-that is, within the time you left it, came to church, and reach home again-then Newton, Herschel, Newcomb, and a vast multitude of great minds, are terrible prevaricators and utterly unworthy of credence. Verily, this dust of the earth, with which the Almighty has magnificently walled you, is in constant and immeasurable motion!

Another property of matter is hardness. But the scientist knows that matter is only relatively hard. Here is, for example, some water, lard, iron, and steel. Is not water soft? Compared with lard, yes; but compared with many gases, water is exceedingly hard. But is not lard soft? Compared with iron, lard is soft; but compared with water, lard is hard. But, surely, iron is hard! Yes, indeed, until you put it alongside of steel, and then iron is measurably soft, for the engineer is habitually speaking of "soft iron." The disguises of matter, you see, are so many and varied as to be intellectually appalling. That is one reason, I take it, why no one is able to state precisely what matter is. All matter partakes of a kind of divine enchantment, and its so-called hardness is one of its enchanting characteristics.

A still further property of matter is solidity. We

speak of solid matter-a solid globe, or a solid rock. If we know what we mean, well and good. But when we talk to a trained physicist or philosopher about matter being "solid," we must needs be on our scientific guard. The best spectroscope, according to Professor Duncan, detects one-half of one millionth of a cubic centimeter of gas, but for determining minute particles of matter, the ultramicroscope is thirty-seven trillion thirty-one billion times more powerful than the spectroscope. Weaponed, therefore, with the spectroscope, the ultramicroscope, the spinthariscope, the electrometer, and a hundred other marvellous instruments, the scientist knows that solidity, as applied to matter, is a mere convenience of speech. Some time ago a friend sent me a load of wood. Not being an expert woodsman, much of that wood is still in our cellar. Once in awhile, urged by true Gladstonian fervour, I go down and chop or saw. Usually, I am easily convinced that my wood is both hard and solid. Consequently, before many sticks are severed, I am perfectly content to walk away and let the scientist argue on as to the solidity or non-solidity of matter. However, my conclusion does not alter the facts even slightly. The wood, of course, is composed of minute particles-molecules, atoms, electrons and all are in such a whirling vortex that Descartes was led to undertake to explain even the formation of the universe itself by his theory of vortices. So the matter composing your body,

as well as the matter composing the billion-miled universe, is only relatively solid.

I will mention only one other characteristic of matter, but one of the most interesting of all, owing to the law of gravity. Matter has the very definite-and indefinite also-property of size. The unit may be the electron, infinitely small, or a star, incalculably large. But the consideration of size, in studying matter, influenced as it is by gravitation, cannot be overlooked. Here is a fountain pen. Suppose I want to increase its size or mass once again. How can it be done? In two ways: first, I may add just as much more fountain pen, doubling the size; second, without increasing the mass at all, I may make the fountain pen weigh just twice as much by doubling the size of the earth. I do not say that I am seriously thinking of undertaking the latter alternative; I only mean to say that scientists say this is one way of doing it. It is interesting to remember, in passing, that Newton did not employ the inductive method in making the greatest discovery of modern times. As thinkers, we believe in the inductive method-getting our facts, then our conclusions. But Newton, by intuition, or genius, or whatever you wish to call it, first got the idea of gravity and then assembled his facts in support of it. "As he foresees," says Carl Snyder, "that the calculations will verify his surmise, his hand trembles so that he must lay down his pen." It is one of the supremely romantic chapters in the