"That is a simple and pictorial outline of what we mean when we speak of the biogenetic law. We need, of course, much more than the one frog-fish before we can erect it into a law. But we have only to look around us and we find similar phenomena as common as pebbles.

"Let us bear in mind that evolution proceeded from certain amphibia to the lizards and from these to the birds and mammals. That is a long journey, but we have no alternative. If the amphibia (such as the frog and the salamander) descend from the fishes, all the higher classes up to man himself must also have done so. Hence the law must have transmitted even to ourselves this ancestral form of the gill-breathing fish.

"What a mad idea, many will say, that man should at one time be a tadpole like the frog! And yet—there's no help in prayer, as Falstaff said—even the human germ or embryo passes through a stage at which it shows the outlines of gills on the throat just like a fish. It is the same with the dog, the horse, the kangaroo, the duck mole, the bird, the crocodile, the turtle, the lizard. They all have the same structure.

"Nor is this an isolated fact. From the fish was evolved the amphibian. From this came the lizard. From the lizard came the bird. The lizard has solid teeth in its mouth. The bird has no teeth in its beak. That is to say, it has none to-day. But it had when it was a lizard. Here, then we have an intermediate stage between the fish and the bird. We must expect that the bird embryo in the egg will show some trace of it. As a matter of fact, it does so. When we examine young parrots in the egg we find that they have teeth in their mouth before the bill is formed. When the fact was first discovered, the real intermediate form between the lizard and the bird was not known. It was afterwards discovered at Solenhofen in a fossil impression from the Jurassic period. This was the archeopteryx, which had feathers like a real bird and yet had teeth in its mouth like the lizard when it lived on earth. The instance is instructive in two ways. In the first place it shows that we were quite justified in drawing our conclusions as to the past from the bird's embryonic form, even if the true transitional form between the lizard and the bird were never discovered at all. In the second place, we see in the young bird in the egg the reproduction of two consecutive ancestral stages: one in the fish gills, the other in the lizard-like teeth. Once the law is admitted, there can be nothing strange in this. If one ancestral stage, that of the fish, is reproduced in the young animal belonging to a higher group, why not several?—why not all of them? No doubt, the ancestral series of the higher forms is of enormous length. What an immense number of stages there must have been before the fish! And then we have still the amphibian, the lizard, and the bird or mammal, up to man.

"Why should not the law run: the whole ancestral series must be reproduced in the development of each individual organism? We are now in a position to see the whole bearing of Haeckel's idea."

In analogy with this, is it not true that every thinking man and woman in the course of his or her development, epitomizes the history of human thought? To be more specific, I take it that you, reader, are an educated man of middle-class origin, and that you have been a socialist for at least six months, and have, of course, read Engels' "Socialism: Utopian and Scientific." Now, is it not a fact that your socialism has developed from Utopia toward Science exactly along the lines Engels has traced for the movement at large? So true was this in my case that for a long time I was inclined to push the biogenetic law too far and to conclude that every socialist had traveled the same road. I still think the law holds here, but not in the narrow way I first applied it.

In the course of my work as an agitator (and socialist agitation is the best School of Socialism) I met many sterling socialists who had never been Utopians as I had. They were born fighters, so to speak, and had been full of the class spirit, and fighting the capitalists in the trade-union and elsewhere in every way they could think of, long before they had ever heard of the ideal of the Co-operative Commonwealth. And these men are among our best and most uncompromising socialists. Here was a hard problem for me. I believed in my law, but it did not seen to cover the cases of these militant socialists. I was long in solving the problem, but I solved it at last.

Socialism has two aspects. As the most vital fact of modern life it is a kinetic force. "Modern Socialism" in Engels' words "is, in its essence, the direct product of the recognition on the one hand, of the class antagonisms, existing in the society of to-day, between proprietors and non-proprietors, between capitalists and wage-workers; on the other hand, of the anarchy existing in production." This is Socialism, the most pregnant actuality in the palpitating life all about us. But, as Engels pointed out, Socialism also has its ideological side. In this sense it may correctly be called a theory, if we bear in mind that it is the virile force of class-feeling, and not the theory, that is going to effect the Social Revolution. Now, every individual socialist does in his development conform to the biogenetic law; but the bourgeois socialist is more apt to epitomize the history of Socialist theory, while the proletarian socialist recapitulates the development of class feeling as a kinetic force from blind and often unavailing hatred of the rich to the fruitful class-consciousness of the Marxian Socialist. The individual may combine these two processes in varying proportions; but in broad outline the bourgeois may be expected to reproduce fairly closely the history of Socialism, as a theory, while the proletarian reproduces the history of Socialism, the great kinetic force.

While, from the standpoint of socialist theory, the statement of Doctor Parkhurst and many others that "Christ was a Socialist" is a manifest absurdity, the historian who traces back the history of Socialism, the kinetic force, will surely be led by the chain of facts to James and Jesus and Isaiah. For they were among those who gave most effective expression to the class hatred which is the lineal ancestor of Marxian Socialism viewed as a kinetic actuality. In this sense Jesus was one of the founders of Socialism.