5. Evidence is of three kinds: evidence of sense, evidence of reason and evidence of hearsay. 6. Proof is evidence inconsistent with an alternative to the assertion. I turn now to the aid given to the case before the jury, and must show how Dr. Mercier’s definitions establish it. The cause of the changes described is the action of certain new habits on a living growing structure of the mammalian body. The effect is the change connected with the preceding change of habit. The result is the changed direction of hair, in other words, new patterns, left when the new habits have been produced, and have been long enough in operation. The reason for the unchanges observed in many instances is the primitive force of the normal direction of growth of the hair. The proof of the thesis is that the changes described in the hair--the evidence--is inconsistent with an alternative assertion. To Some Critics. It may save time and trouble if replies are given in anticipation to certain classes of critics. I refer of course to those who are well-informed in their branch of knowledge. To those of high authority and learning, those who ride on white asses and that sit in judgment, who may seek to throw the case into chancery, saying, “This will never do, it contradicts current biological opinion.” I can only meekly reply that current or orthodox opinion is frequently wrong, or (shall I say) seldom right, and that the history of human thought is strewn with examples which may justify my impertinent reply. To another who says, “I daresay you are right in your claim, but there are too many metaphors,” I would suggest that, so long as metaphors are not used as arguments, the more metaphors--within limits--the clearer the meaning of the statement. To him who grudgingly allows, “I think you have proved your case--but what does it prove?” I reply that it proves what it set out to prove, no more and no less, and it is an integral part of proof of a larger claim. And if he further grumble that these matters have no interest for him, one may ask him to live and let live. “What have I now done in comparison of you, is not the gleaning of your grapes of great Ephraim better than the vintage of this little Abiezer?” To the man who reads the preface and the headings of the chapters, glances at the illustrations, detects one split infinitive, two misspellings and three errors of punctuation, goes home to tea and writes his opinion--it may suffice to remind him of “that curious mental state which looks past problems without seeing them.” I will conclude this section with a parable.