Exclusive and long-continued devotion to any special line of study is liable to lead to forgetfulness of other, even kindred, lines--almost, in extreme cases, to a kind of atrophy of other parts of the mind. There is the example of Darwin and his self-confessed loss of the aesthetic tastes he once possessed. Nor are scientific studies the only ones to produce such an effect. The amusing satire in _The New Republic_ has, perhaps, lost some of its tang now that the prototype of its Professor of History is almost forgotten, but it has not lost its point. Lady Ambrose tells the tale: "He said to me in a very solemn voice, 'What a terrible defeat that was which we had at Bouvines!' I answered timidly--not thinking we were at war with anyone--that I had seen nothing about it in the papers. 'H'm!' he said, giving a sort of grunt that made me feel dreadfully ignorant, 'why, I had an excursus on it myself in the _Archaeological Gazette_ only last week.' And, do you know, it turned out that the Battle of Bouvines was fought in the Thirteenth Century, and had, as far as I could make out, something to do with Magna Charta." It is, however, among writers on biological subjects that we find the most salient instances of this contraction. With extraordinary self-abnegation they seem, in the contemplation of the problem with which they are concerned, to forget that they themselves are living things, and, more than that, the living things of whom they ought to know and could know most, however little that most may be. When the biologist begins to philosophise as, after the manner of his kind, he often does, he should leave his microscope and look around him; whereas he often forgets even to change the high for the low power. Thus he limits his field of vision and forgets, when attempting his explanation, that it is only _within a system_ that he is working. Professor Ward, in _Naturalism and Agnosticism_, says: "From the strict premisses of Positivism we can never prove the existence of other minds or find a place for such conceptions as cause and substance; for into these premisses the existence of our own mind and its self-activity have not entered. And accordingly we have seen Naturalism led on in perfect consistency to resolve man into an automaton that goes of itself as part of a still vaster automaton, Nature as mechanically conceived, which goes of itself. True, this mechanism goes of itself because it _is_ going, and being altogether inert, cannot stop or change. How it ever started is indeed a question which science cannot answer, but which, on the other hand, it has no occasion to ask: time, its one independent variable, extends indefinitely without hint of either beginning or end. Such a system of knowledge, _once we are inside it_, so to say, is entirely self-contained and complete."