efore 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 fight