I. Haeckel and His Opponents

But it is also by no means easy for the human mind to construct for itself conceptions in accordance with Nature as regards the unfoldment of the single organism from the germ up to the developed condition. We can see this from the ideas which a scientist like Albrecht von Haller (1708-1777) and a philosopher like Leibnitz (1646-1716) formed about this development. Haller maintained the view that the germ of an organism already contains in miniature, but fully and completely formed in advance, all the parts which make their appearance during its development. Thus, development is taken to be not the formation of something new in what is already present, but the unfolding of something that was already there but invisible to the eye because of its minuteness. But if this view were correct, then in the first germ of an animal or vegetable form all following generations must be already contained like boxes one inside the other. And Haller actually drew this conclusion. He assumed that in the first human germ of our root-mother, Eve, the entire human race was already present in miniature. And even Leibnitz also can only imagine the development of men as an unfoldment of what already exists: “So I should opine that the souls, which some day will be human souls, were already there in germ, like those of other species, that they existed in man's ancestors up to Adam, therefore from the beginning of things, always in the form of organised bodies.”