progression. But most species actually increase in number very slowly, if at all. Now and then some insect or weed escapes from its enemies, comes under favorable food conditions, and multiplies with such rapidity that it threatens to ravage the country. But as it multiplies it furnishes an abundance of food for the enemies which devour it, or of food and place for the parasites in and upon it; and they increase with at least equal rapidity. Hence while the vanguard increases prodigiously in numbers, because it has outrun these enemies, the rear is continually slaughtered. And thus these plagues seem in successive generations to march across the continent.

And yet even they give but a faint idea of the reproductive powers of plants and animals. The female fish produces often many thousands, sometimes hundreds of thousands of eggs. Insects generally from a hundred to a thousand. Even birds, slowly as they increase, produce in a lifetime probably at least from twelve to twenty eggs. Now let us suppose that all these eggs developed, and all the birds lived out their normal period of life, and reproduced at the same rate. After not many centuries there would not be standing room on the globe for the descendants of a single pair.

Again, of the one hundred eggs of an insect let us suppose that only sixty develop into the first larval, caterpillar, stage. Of these sixty, the number of members of the species remaining constant, only two will survive. The other fifty-eight die-of starvation, parasites, or other enemies, or from inclement weather. Now which two of all shall survive? Those naturally best able to escape their enemies or to resist unfavorable influences; in a word, those best suited to their

conditions, or, to use Mr. Darwin's words, "conformed to their environment."

Now if any individual has varied so as to possess some peculiarity which enables it even in slight degree to better escape its enemies or to resist unfavorable conditions, those of its descendants who inherit most markedly this peculiar quality or variation will be the most likely to escape, those without it to perish. If a form varies unfavorably, becomes for instance more conspicuous to its enemies, it will almost certainly perish. Thus favorable variations tend to increase and become more marked from generation to generation.

Now it has always been known that breeders could produce a race of markedly peculiar form or characteristics by selecting the individuals possessing this quality in the highest degree and breeding only from these. The breeder depends upon heredity, variation, and his selection of the individuals from which to breed. Similarly in nature new species have arisen through heredity, variation, and a selection according to the laws of nature of those varying in conformity with their environment. And this Mr. Darwin called natural, in contrast with the breeder's artificial, "selection," arising from the "struggle for existence," and resulting in what Mr. Spencer has called the "survival of the fittest."

Let us take a single illustration. Many of the species of beetles on oceanic islands have very rudimentary wings, or none at all, and yet their nearest relatives are winged forms on some neighboring continent. Mr. Darwin would explain the origin of these evidently distinct wingless species as follows: They are descended from winged ancestors blown or otherwise

transported thither from the neighboring continent. But beetles are slow and clumsy fliers, and on there wind-swept islands those which flew most would be blown out to sea and drowned. Those which flew the least, and these would include the individuals with more poorly developed wings, would survive. There would thus be a survival in every generation of a larger proportion of those having the poorest wings, and destruction of those whose wings were strong, or whose habits most active. We have here a natural selection which must in time produce a species with rudimentary or aborted wings, just as surely as a human breeder, by artificial selection can produce such an animal as a pug or a poodle. These, like sin, are a human device; nature should not be held responsible for them.

But you may urge that the variation which would take place in a single generation would be, as a rule, too slight to be of any practical value to the animal, and could not be fostered by natural selection until greatly enhanced by some other means. Let us think

a moment. If ten ordinary men run in a foot-race, the two foremost may lead by several feet. But if the number of runners be continually increased the finish will be ever closer until finally but an atom more wind or muscle or pluck would make all the difference between winning and losing the prize.

Similarly the million or more young of any species of insect in a given area may be said to run a race of which the prize is life, and the losing of which means literally death. The competition is inconceivably severe. How indefinitely slight will be the difference between the poorest of the 2,000 or 20,000 survivors

and the best of the more than 900,000 which perish. The very slightest favorable variation may make all the difference between life and sure death. And yet these indefinitely slight variations continued and aggregated through ages would foot up an immense total divergence. The chalk cliffs of England have been built up of microscopic shells.

I have tried to give you very briefly a sketch of the essential points of Mr. Darwin's theory of evolution. But you should all read that marvel of patience, industry, clear insight, close reasoning, and grand honesty, the "Origin of Species.' I have no time to give the arguments in its favor or to attempt to meet the objections which may arise in your minds. I ask you to. believe only this much; that the theory is accepted with practical unanimity by scientific men because it, and it alone, furnishes an explanation for the facts which they discover in their daily work. And this is the strongest proof of the truth of any accepted theory.

Inasmuch as it is accepted by all scientists and largely by the public, it is certainly worth your while to know whether it has any bearing on the great moral and religious questions which you are considering. And in these lectures I shall take for granted, what some scientists still doubt, that man also is a product of evolution. For the weight of evidence in favor of this view is constantly increasing, and seems already to strongly preponderate. Also I wish in these lectures to grant all that the most ardent evolutionist can possibly claim. Not that I would lower man's position, but I have a continually increasing respect for the so-called "lower animals."

Now if the theory of evolution be true, and really

only on this condition, life has had a history; and human history began ages before man's actual appearance on the globe, just as American history began to be fashioned by Anglo-Saxons, Danes, and Normans before they set foot even in England. We study history mainly to deduce its laws; and that knowing them we may from the past forecast the future, prepare for its emergencies, and avoid or wisely meet, its dangers. And we rely on these laws of history because they are the embodiment of ages of human experience.

Whatever be our system of philosophy we all practically rely on past experience and observation. Fire burns and water drowns. This we know, and this knowledge governs our daily lives, whatever be our theories, or even our ignorance, of the laws of heat and respiration. Now human history is the embodiment of the experience of the race; and we study it in the full confidence that, if we can deduce its laws, we can rely on racial experience certainly as safely as on that of the individual. Furthermore, if we can discover certain great movements or currents of human action or progress moving steadily on through past centuries, we have full confidence that these movements will continue in the future. The study of history should make us seers.

But the line of human progress is like a mountain road, veering and twisting, and often appearing to turn back upon itself, and having many by-roads, which lead us astray. If we know but a few miles of it we cannot tell whether it leads north or south or due west. But if from any mountain-top we can gain a clear bird's-eye view of its whole course, we easily dis