It is very instructive to note how Virchow shifted his position a little in accordance with the time. In his judgment science _had_ to make peace. It had to make concessions in certain directions. In 1863 he had spoken of the “ruling Churches.” Now, in 1877, he speaks of the freedom of science in the “modern State.” The great _Kulturkampf_ had set in. The Church was for the time being powerless in face of the State. Hence Virchow now plays off the State as the guardian of his tabooed province. This time Darwinism is supposed to be threatening the virgin field in which we exact scientists make our peace with the State. At the right moment he adroitly points out that the Social Democrats have taken to Darwinism. Every man on deck, then. That must not go any further. At the bottom it was the old contest. If one lays down as a general principle that the scientific pursuit and presentment of truth has to respect neutral provinces and make concessions, every change in current affairs will demand a fresh application of it. To-day it is some Church or other, to-morrow a State, the next day the momentary code of morals, and lastly some bumbledom or other that renews the prohibition to dissect corpses, because our dissecting knives disturb the peace of mind of our Philistine neighbours. Haeckel published a sharp reply to Virchow (_Free Science and Free Teaching_, 1878), in which he sought to show amongst other things, taking his stand on his political principles, that Socialism and Darwinism have nothing to do with each other. I will not go more fully into the controversy here. If one province of knowledge is to receive light from another at all, we must admit that there is only one general truth. All stationary or reactionary political interest is irreconcilable with the theory of evolution. That is clear from the very meaning of the words. As to the direction in which we must seek real political and social progress opinions are bound to differ very considerably; it may be shown that the laws of evolution which have selected the various species of plants and animals can only be used very sparingly and cautiously for the promotion of human progress. But I believe that is quite an immaterial point in this matter of Virchow’s attack. The real influence of Darwinism on political questions is not the chief question. The principle we have to determine is whether the freedom of scientific research and the teaching of what the individual student believes he has discovered to be true are to have “external” restrictions or not. The question is whether inquiry and teaching are to be regarded merely as things “tolerated” and interfered with at will amongst the various elements of modern life; or whether they are not to be considered the very bed-rock of civilisation, and every agency that has power for the moment is not doomed whenever it comes into collision with them.