One day I enjoyed luncheon with an old friend and we essayed a theme hard as high. I doubt if what we talked about would be intelligible to all readers, and I am none too sure that we understood ourselves, but as there seems to be a public craving for such intellectual flights I shall venture a brief digest of our talk.

But first a word about this friend. He is a finished product of an older civilization than that of New York. Whenever I walk with him in what Mr. Henry James carefully describes as "the Fifth Avenue," I feel as George Warrington did when he walked with Pendennis: "I feel as if I had a flower in my button-hole." His life moves entirely among the most precious objects of art and literature, among masterpieces of sculpture, painting, printing, book-binding, and what not. And withal he is very much alive and in touch with the world in which we live. After this introduction I shall let him rail at our wonderful civilization.

"Invention is the curse of the world. With our machinery and efficiency we are speeded up so that life has been spoiled. I wonder who made the first invention."

That led to a pretty discussion. After dealing with the subject back and forth, we decided that the most guilty man the world had ever known was the man who invented the first wheel—who discovered that something round could be made to revolve. That discovery was the starting-point of all our modern machinery and destructive speed. Take away the wheel and the world would come to a standstill. I joined him in reviling that far-off, long-ago inventor.

Then we followed the first wheel—was it perhaps a potter's wheel?—and followed its deadly evolution. The oldest wheels recorded in art are the wheels of chariots—war chariots, of course. There you see the earliest tendency of the war spirit that culminated in our great war of machinery. The warrior used the wheel to make a chariot to give him an advantage over his enemies. The development of the wheel has been involved with war from the chariot wheel to the whirling propellers of aeroplanes.

This line of thought led us to realize that war is the great stimulator of invention. Such inventions as the aeroplane were perfected more completely in the four years of war than they would have been in centuries of peace. We found that it would be easy to hold a brief for war as the force that has been perfecting our civilizations of many inventions. (Solomon said, "Man was born upright, but he has sought out many inventions.")

But what does it profit us if the highest use we make of our inventions is to increase our efficiency in battle? If we invent long enough and cleverly enough, we may yet start a war in which we will destroy the human race.

That awful possibility is the present preoccupation of scientific research.

We are told that the next advance of science may be the discovery of how to release atomic energy. Molecular energy, brought under control through the unstable equilibrium of certain artificial compounds, has given us the gun, the cannon, the bomb, the mine, and all the other infernal masterpieces of high explosives.

What would atomic energy give us?

Sir Oliver Lodge has told us that the amount of atomic energy in one ounce of matter would be sufficient to raise the fleet that was anchored in Scapa Flow to the top of the highest mountain in Scotland. Then what would happen if we released the atomic energy in tons of matter? It is certain that if man ever masters the secret he will go in for quantity production of atomic energy. And what then?

To realize the dire possibilities of this thought we must digress and approach it from a new angle.

Those of us who date our meagre scientific knowledge from reading done in the last quarter of the past century had our imaginations fired by the nebular hypothesis. I do not know whether it has current authority, but it was a wonderful theory and will serve our purposes to-day. I quite realize that if I am to avoid destructive scientific criticism, I should consult some up-to-the-minute scientist and get my facts right, but a care-free conversation between friends is not to be "cabined, cribbed, confined" in that way. If I let the public overhear our talk I shall expect them to listen with unquestioning courtesy. I have purposely avoided asking the aid and leading of a scientist in this matter because most of the scientists of my acquaintance live wholly within three dimensions and have put a padlock on the third. But the conversation of friends demands the freedom of a fourth dimension in which our Space and Time are but points on the superfices of a comprehended Infinity and Eternity. Now will you be good!

To return to the nebular hypothesis. According to it the planets were flung from the whirling mass of the sun as it was in the process of shrinking. Neptune was naturally the first to be thrown off and the others followed in due order. Would it not be reasonable to suppose that the oldest of the planets—the one that was first thrown off from the sun and is farthest from it—would be the first to cool and become habitable? But it is known that all the outer planets except Mars are in a gaseous state. Is there any possible explanation of this curious state of affairs—this apparent contradiction of logical results which gives us the last planets solid and the earlier planets gaseous?

If the earlier planets cooled to solid form and developed life analogous to ours, it is probable that they lived by war and invention. If these forces developed as with us, it is probable that a day came on each of the old planets when its puny inhabitants got control of atomic energy, started a last war, and blew their planet back to its constituent gases. Atomic energy is probably a force of the fourth dimension and if released in three dimensions would have about the same effect as that of a high-explosive shell passing through a piece of tissue paper and exploding as it passed.

The destructive discovery progressed across the ecliptic until only four planets are left in solid form. Mars may now be preparing for the last proud war and we are on the verge of a culminating discovery of the disruptive force of atomic energy. Unless something checks our rage for discovery, and war is within reasonable possibility, the whole planetary system may be blown back to chaos—and so fulfil Poe's amazing figure of the alternation from Chaos to Order and from Order to Chaos as "the systole and diastole of the heart of the Infinite."

After this exhausting flight my friend faced the High Cost of Living in the form of the waiter's check, passed me a cigar that cost a dollar, and in a humble taxi we joined the whirling civilization that speeds on wheels along "the Fifth Avenue," and doubtless whiles away its idle time in discussing the war and who won it.