This illustration of the rules of evidence, when applied to scientific inquiries, leads me to refer to one of the favorite postulates of the evolution school. We are often told that it ought to be no objection to the doctrine of evolution that it is new, or startling, or contrary to other previous theories of the existence of species. We are reminded again and again that Galileo's grand conception was scouted as an irreligious as well as an irrational hypothesis, and that the same reception attended the first promulgation of many scientific truths which no intelligent and well-informed person now doubts.[2] Then we have it asserted that the doctrine of evolution is now accepted by nearly all the most advanced and accomplished natural philosophers, especially those of the rising scientists who have bestowed most attention upon it. Upon this there are two things to be said: First, it is a matter of very little consequence that the learned of a former age did not attend to the proofs of the law of gravitation, or of any other new theory of physics, as they should have done, and that they consequently rejected it. Their logical habits of mind, their preconceived religious notions, and many other disturbing causes, rendered them incapable of correct reasoning on some particular subject, while they could reason with entire correctness on other subjects. Secondly, the extent to which a new theory is accepted by those whose special studies lead them to make the necessary investigations, does not dispense with the application of the laws of evidence to the facts which are supposed to establish the theory. The doctrine of evolution addresses itself not only to the scientific naturalist, but to the whole intelligent part of mankind. How is one who does not belong to this class of investigators to regulate his belief in the theory which they propound? Is he to take it on their authority? or is he, while he accords to their statements of facts all the assent which as witnesses they are entitled to expect from him, to apply to their deduction the same principles of belief that he applies to everything else which challenges belief, and to assent or dissent accordingly? No one, I presume, will question that the latter is the only way in which any new matter of belief should be approached. I have not supposed that any scientist questions this; but I have referred to the constant iteration that the doctrine of evolution is now generally admitted by men of science, that the assertion, supposing it to be true, may pass for just what it is worth. It is worth this and no more: that candid, truthful, and competent witnesses, when they speak of facts that they have observed, are entitled to be believed as to the existence of those facts. When they assume facts which they do not prove, but which are essential links in the chain of evidence, or when the facts which they do prove do not rationally exclude every other