One fine day a small speck of dust(it weighed only 6,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 tons, which is very little as such luminaries go)wandered forth from its ancient mother, the Sun, and set up in business for itself.

The event did not cause much of a stir in Heaven, for the new recruit for stellar honors was so hopelessly insignificant that none of the older stars, which rived in a distant and more respectable part of the universe, were able to notice the arrival of their little brother, unless their inhabitants(as seems hardly likely)were possessed of better telescopes than those which to-day stand in our own observatories

But perhaps we had better not inquire too closely into the more humiliating aspects of the case, for when all is said and done we are all of us prisoners on this tiny round ball And, whether we like it or not, that little planetis our home and will probably continue to be our home for a good long time.

I do not, mean to imply that we shall never be able to venture forth into space and pay an occasional visit to other parts of the firmament. But it is doubtful whether any of the other planets would lend themselves for the purpose of permanent settlement by denizens of the earth.For either they are altogether uninhabitable(as most of the planets of our solar system seem to be)or if they have developed a life of their own, it must be much older than that which exists on our own floating prison and we should be very much out of place in a country which had started to learn the rudiments of civilization one or two million years before ourselves.

And that reminds me of something that has puzzled me for a long time.

Why are people so tremendously interested in detective stories?

“It is the mystery that attracts them,”is the usual answer, or“It is the fascination of watching a single vague clew develop into an iron chain of incontrovertible evidence.”

For all I know, that may be the true reason. But in that case I wonder why more of them don't take up the study of geology, for the story of our planet is one endless series of the most magnificent riddles and only a few of them have thus far been solved.The others obstinately refuse to divulge their secrets, but in all fairness to them it should be said that there is not a single one among all these various puzzles to which there is not a key.

The people of ancient times knew this and they forced the rocks and the plains which were their home to tell them a great many things about their origin and their early past, which were of tremendous importance. But their successors, the humble folk of the Middle Ages, although they were great heroes on the field of battle, were terrible cowards within the Realm of Reason.They asked no questions, but meekly accepted what they were told out of an old book, and curiosity about the planet on which they lived was regarded as nothing less than sacrilege.

To-day the Middle Ages have been relegated to the museum of historical curiosities. Another ten or twenty thousand years and the little crust on which we crawl around with such energy will hold no more mysteries than an aspirin tablet or a pumpkinpie.

It may seem that I am a little too generous with my thousands and hundreds of thousands of years, and juggle a bit too freely with the centuries. But that can hardly be helped in these days when fresh prehistoric discoveries have almost quadrupled the period during which we can speak of“history”in the accepted sense of the word as a“continuous methodical record of past events.”Besides, such a feeling of the vast duration of the existence of all the things with which we are familiar is very good for the soul and teaches us humility and patience.When we begin to realize that it took our ancestors something like 500,000 years to learn to walk on their hind legs, we feel a little more tolerant towards our own contemporaries when they fail to solve some important problem in less time than we think they ought to take and we get a better slant upon ourselves.We cease to be so terribly important.We become mere upstarts—creatures which did not make their appearance upon the surface of the planet until millions and millions of years after the majority of the other arrivals—rulers of the universe who only day before yesterday were admitted through the front gate.

As for the different steps which nature took to arrive at this fine conclusion-on-two-feet, we are still ignorant about many of the details, but in a general way we have at least a suspicion of how it came about.

It all began as soon as the outer crust of our planet had sufficiently cooled to support some sort of life. It was rapidly populated by an endless variety of plants and by multitudes of armor-clad, sightless creatures which spent their entire existence in the water and were the undisputed masters of the earth.

We know that some of them remained faithful to the sea and became the ancestors of the fishes upon which we feed to-day;that others developed wings and took to the air and became the grandparents of our modern birds. We have discovered that others, which belonged to the same family as the lizards and serpents of our own day, came to such great estate that for a long while it looked as if our planet was to be permanently dominated by reptiles.For the climate of that period(and please try to think in terms of millions of years and forget all about the dates in your history book, which represents only a couple of seconds in the calendar of eternity)—the moist, damp climate of that period greatly favored the development of gigantic monsters, which were as much at home in the water as they were on land and looked and behaved like animated dreadnoughts.

We also know that the period during which the air, the water and the land were the exclusive domain of beasts that measured forty or fifty or sixty feet and that had stomachs as large as the cabin of a fair-sized yacht, was suddenly followed by an era during which not a single one of them was to be found in any part of the globe.

How and in what way those early rulers of the world came to their ignominious death and why to-day they survive only in pocket-size editions—that is something of which, until a few years ago, we understood nothing at all. Now at last we are beginning to realize that there was not one single cause, but that there were a large number of complicated and interacting reasons and that the Law of the Inevitable Top-Heaviness of Things, which rules all living matter, had a great deal to do with it.

You know what is happening to-day in the realm of arms. All the good intentions in the world and all the Leagues of Nations in the world are not half as important in making the world safe the reasonably inclined citizens as the plain, prosaic fact that the machinery of modern war has grown so cumbersome, has become so incredibly top-heavy, that soon through sheer bulk it will no longer be able to float nor fly nor ride nor go on foot, but will be obliged to wobble and waddle and groan and grunt like a truck in the mire.

The creatures whose ridiculous skeletons grin at us to-day from the show-cases of those museums which are possessed of sufficient floor-space for such an exhibition went through a similar development.

They increased their size and strengthened their armaments until they could neither walk nor swim and were doomed to wade through the mud and slime of those endless marshlands which during that period of the earth's history covered so great a part of the world and which offered no more substantial fare than reeds and seaweeds.

Then when a change in the climate occurred(and sudden and violent changes in climate were more apt to occur then than they are now, owing to a more equitable division of oceans and continents at the present moment),these slow-witted monsters could turn neither to the sea nor to the land in search of a new means of support. And so they were doomed to perish in such a thoroughgoing and efficient manner that of all the countless billions of saurians, which for so many millions of years were the undisputed masters of our planet, not a single one lived to see the coming of the great mammals and the final appearance of man.

That is the story as it is usually told, but I wonder whether it is the whole of the story—whether there is not another angle from which we have never looked at it and which is quite as important as any of the usual excuses for their untimely demise.

Climatic changes no doubt exercise a very important influence upon the comfort and happiness of all living creatures, from microbes to mules.

But climatic changes, unless they are so terrific that they amount to absolute catastrophes(like those that seem to have followed in the wake of the extinction of our former moons),need not always be fatal. Indeed, they have much in common with financial crises, In both cases, those who are unprepared perish.

But those who have taken measures to protect themselves against sudden emergencies can stand the strain and survive.

And this remark offers me an excellent opportunity to introduce the real hero of our story and refrain from further philosophizing, which is pleasant for the author but rather hard on the reader.

Alas!when the creature made its first appearance, it didn't look the least little bit like a hero, but very much like one of the baboons or chimpanzees or orang-outangs which regard us in such a melancholic fashion from behind the iron bars of the Zoo.

I do not mean to imply that the human race has descended directly from one of these man-like apes or that human beings are merely gorillas who have done rather well in the world and who have reason to feel slightly ashamed of their unfortunate grandparents. That would make the matter of descent altogether too simple.

But according to the hest of our information, millions of years ago the chimpanzees and orang-outangs and baboons and we ourselves possessed one common ancestor. One part of the family evolved into something a little higher and finer and sometimes even a little nobler, while other branches contented themselves with remaining exactly what they had been in the days of the mammoth and the cave-bear, great big shambling creatures who live in the murky tenements of primeval forests or who are caught and put into cages to be shown to their gaping cousins of the big cities as a dreadful warning of the fate that awaits those who are too lazy or too incompetent or too dull to make the best of their opportunities.

As for the actual process of change which elevated man from the undignified position of a long-tailed quadruped, at the mercy of almost every one of its better armed neighbors, to the dignity of the tailless, two-footed master of the universe, there once more it is such a short time since we have been allowed to study that subject scientifically without running the risk of being burned at the stake for our troublesome curiosity that we are still profoundly ignorant about many of the most important details of this marvelous metamorphosis.

All the same, a sufficient amount of work has been done to make it possible for us to get at least a general idea of what happened when our great-great-grandparents took their courage into both their recently acquired hands and decided to break away from the dull routine of mere animal existence.

The period during which our ape-like ancestors came for the first time into international prominence was an era of a warm and even climate when there was more water on the earth than there is to-day and when small stretches of dry land, densely covered with forests, took the place of our present continents. These forests were inhabited by diverse tribes of a common simian origin.They were tree-dwellers and marvelous acrobats.For their safety depended entirely upon their ability to leap vast distances without the slightest degree of error.Even if it were not exactly necessary for them to be nimble-witted, they were forced to be more so that their heavier armed enemies or he eaten by the latter.

Now if all had gone well and the world had remained as it was(which to the great horror of many honest people it never does)there is no reason why the simian race should not ultimately have inherited the earth and have become the undisputed rulers of this planet, as the gigantic reptiles and the gigantic mammals had been before them.

But some ten million years ago the earth seems to have suffered another change. As a result of this the waters receded somewhat and the land increased in size, while the general temperature of the world became slightly lower and the air became less moist.In consequence whereof, conditions became less favorable for vegetable life and soon(that is to say, after the inevitable hundreds of thousands of years)vast stretches of land which since time immemorial had been covered with forests began to show occasional gaps.And finally the woods shrank until they had become mere little islands of trees, surrounded on all sides by grass-covered plains and snow-covered mountains.

It was then that our own ancestors had their chance.

Whereas until that moment they had been able to make an easy living, moving rapidly from one part of the endless forests to another, they now found themselves deprived of their old means of locomotion and were as helpless as railroad trains without tracks.

To make conditions worse, the ever increasing height of the mountain ridges was beginning to raise a series of barriers which divided the world into definite terrestrial compartments from which there was no escape except for the birds and a few of the hardier varieties of insects and butterflies.

Under these conditions the law of the survival of the fittest began to operate with very remarkable results. By far the greater number of the ape-like creatures submitted to the inevitable.The more intelligent tribes, however, fought back.

And they fought back with the only means at their disposal.

They fought back with their brains.

It was then that our race passed through its most severe crisis and then that the future fate of mankind was decided for good and all.

It was then that the earliest ancestor of man turned inventor.

Now when we use the word“invention”in the modern sense, we think at once of flying machines and radios and complicated electric contrivances. But it is of quite a different sort of invention that I want to speak at the present moment.I want to tell you of those basic and elementary inventions which, curiously enough, only one sort of mammal seems ever to have been able to devise and which gave that particular species a chance not only to go on living when most of the others died, but furthermore to claim for itself and its descendants a position of such absolute preminence that nothing will ever be able to shake it unless man, in his folly and greed, continues his present policy of violence and warfare and allows himself to be eaten out of house and home by some particularly industrious mad prolific family of insects—while he himself is engaged in the usual pursuit of murdering his neighbors.

Right here of course one might interrupt me with the questions,“How about the inventive power of animals?Haven't the birds and the wasps and the ants and some of the fishes invented nests?Haven't the beavers become veritable architects mad learned to build dams that are as efficient as anything made by human hands?Don't spiders construct all sorts of hunting apparatus that are the terror of their prey?What about the traps many of the insects dig to capture their prey?”And so on and so forth.

To which I could only answer yes. The business of inventing is not exclusively restricted to that part of the animal kingdom which is known as Man.Several of his rivals have also“invented”things.But there is a vast difference between the inventions of ordinary animals and those of our own species.

The ordinary animals have never originated more than a single new idea. That one effort seems to have exhausted their imaginative powers.Thereafter they merely repeated themselves in an absolutely monotonous and mechanical fashion.

The nests and webs and dams they are building in the year of grace 1928 are not different from the nests and webs and dams they made in the year 192,800,000 B. C.If we allow them to survive, which is doubtful, they will still be building the same nests and webs and dams 192,800,000 years hence.For their so-called inventions are merely part of their daily quest for food, as is shown by the fact that those same animals, in a state of captivity, cease almost immediately to construct anything at all and happily live upon the fare which is provided for them by their keepers.Whereas man seems to have realized at a very early moment that there was something more to life than the mere business of getting enough to cat and to drink;that he could not hope to devote himself to matters of the spirit without a great deal of leisure;that this leisure could be achieved only by freedom from toil and drudgery;that this freedom from toil and drudgery could be accomplished only by an endless variety of“inventions”which had to be based upon the unlimited multiplication and extension of those few and slender powers with which nature had endowed him at the time of his birth.

That is a pretty big sentence, but it is the last of the big sentences in this book, and, furthermore, it has got to be a big one. One cannot discuss the problems that lie at the very root of existence as if one were talking about the weather or the coming elections.It takes big words to explain big ideas.But once you understand what I am trying to say on this page, you will understand everything else in the present book and so it won't do you any harm to reread the last hundred words a couple of times.

The human race, as we know it at present, started with one enormous initial advantage. Its ancestors, through their mode of living among the branches of the trees, had been obliged to develop a high degree of mental alertness and quickness of decision long before any of the other animals had been placed in a similar desperate position.With those others, brute force had been pitched against brute force.With the apes it had been a question of nimble fingers and even nimbler minds, holding their own against claws and beaks that could break a tree into splinters.

When through the disappearance of their former haunts these creatures had suddenly been forced to change their mode of existence, they had already accumulated such terrific versatility in the use of their hands and feet that it was comparatively easy for them to use their hind-legs for the purpose of standing upright, while their fore-feet supported their bodies among the low shrubs and the high reeds through which they must now begin to move in quest of food.

When finally they found themselves almost completely deprived of their verdant bungalows and were forced to dwell entirely in the plains, they were no longer a mere tribe of treedwelling animals but a strange new sort of creature which was rapidly learning the incredibly difficult art of walking on its hind-legs without any support whatsoever and which was therefore able to relieve its fore-paws from all further duties as auxiliary engines of locomotion and could use them entirely for a number of purposes, like“holding”and“carrying”and“tearing”,which thus far had been performed in a clumsy and most unsatisfactory fashion by the teeth of their powerful jaws.

That was the first step along the road of progress and it was directly responsible for the second one, to which the bulk of this book is devoted, and which consisted in that gradual process of multiplication of the powers of our feet and hands and eyes and ears and mouth, and in strengthening the endurance of our skin, through which we have attained our present superior position in the animal kingdom and which has made us the undisputed rulers of the star that serves us both as a home and as a prison.

But that was not all. At the very moment when our ancestors were rudely put before the choice of remaining what they were and perishing, or becoming something a little better and surviving, nature came to their aid.For not only did the climate change sufficiently to bring about a shrinkage of the forests, but the lessening of the available water supply and the increasing height of the mountain ranges(and mayhap some other reasons which we have not yet discovered)caused such a sudden decline in the general temperature of the earth that another of those so-called“glacial periods”took place, which ere then at regular intervals had covered the greater part of both the northern and the southern hemisphere with thick sheets of ice and snow and had forced all plants and animals to withdraw to a comparatively narrow strip of land along both sides of the equator.

It is a fact quite often overlooked in our modern times(when work hasbecome almost the sole relief of the boredom created by a purely mechanicalcivilization)that everything that exists is innately lazy. Since it is the businessof living matter to go on living, it will make very.great efforts to survive.But once this primary duty has been attended to, there is not a plant nor an animal nor even a piece of coral which does not greatly prefer peace and quiet to activity and bustle.No lion or tree or shrimp ever works when he or she or it can enjoy the agreeable joys of doing nothing at all.And man too would never have achieved his present great victories if he had not been spurred into action by the brutal necessities that were inevitably associated with those endless periods of time when only one-eighth of the surface of the earth was inhabitable.

Never before or afterwards has man made such enormous strides in every field of development as during those ghastly stretches of time when glaciers crept down upon him from all sides, when the summers had shrunk to a mere handful of days, when all the land from the North Pole to the Alps was one vast icefield.

We bear a great deal about that proverbial“school of hard knocks”which is supposed to be the best of all possible institutions of learning. To judge, however, by the results, the“school of the glaciers”was the most thoroughgoing training-school which the human race ever attended.

Article I of its icy curriculum read:“Thou shalt either use thy brain to the utmost possibility of its development, or thou shalt perish.”

Our ancestors of those long forgotten days were low-browed brutes, evil-smelling savages, creatures that were very little different from most of their animal neighbors. But we can forgive them a great deal when we remember that they had the courage to take up the uneven battle against nature and were willing to fight it out to a victorious finish against odds that nowadays would seem hopeless.

And how they did this by the very simple process of multiplying to an almost unlimited degree the powers that lay dormant in their hands and feet and eyes—that I shall now try to tell you.