Prof. Huxley had said that the evidence for the theory of evolution is demonstrative, and that it is as well based in its proofs as the Copernican theory of astronomy. “This,” says Mr. Youmans, “is thought to be quite absurd. It is said that Huxley may know a great deal about animals and fossils, but that obviously he knows very little about logic. His facts being admitted, a great deal of effort has been expended to show that he does not understand how to reason from them.” We agree with the critics here alluded to, that Prof. Huxley’s assertion concerning the demonstrative character of his proofs is “quite absurd.” As to his knowledge of logic, there might perhaps be two opinions; for a man may know logic, and make a wilful abuse of it; but it is more charitable to assume that his illogical conclusions proceed from ignorance rather than malice. After all, we are not concerned with the person of the professor, but with his lectures; and, whatever logic he may know, his lectures are certainly not a model of logical reasoning. The passage which Mr. Youmans extracts from Dr. Taylor’s letter, and which he vainly endeavors to refute, is as follows: “Indeed, to affirm, as he [Prof. Huxley] did, that evolution stands exactly on the same basis as the Copernican theory of the motions of the heavenly bodies, is an assertion so astounding that we can only 'stand by and admire’ the marvellous effrontery with which it was made. That theory rests on facts presently occurring before our eyes, and treated in the manner of mathematical precision. It is not an inference made by somebody from a record of facts existing in far-off and pre-historic, possibly also pre-human, ages. It is verified every day by occurrences which happen according to its laws. But where do we see evolution going on to-day? If evolution rests upon a basis as sure as astronomy, why do we not see one species passing into another now, even as we see the motions of the planets through the heavens?... We know that astronomy is true, because we are verifying its conclusions every day of our lives on land and on sea. We set our clocks according to its conclusions, and navigate our ships in accordance with its predictions; but where have we anything approaching even infinitesimally to this, with evolution?” Mr. Youmans remarks that the author of this passage is said to be a man of eminence and ability. “That may be,” he adds, “but he certainly has not won his distinction either in the fields of logic, astronomy, or biology.” To prove this, he makes the following argument: