Hence, if our definition is to be interpreted strictly, we must include man and all his ways and works under the head of Biology; in which case, we should find that psychology, politics, and political economy would be absorbed into the province of Biology.  In fact, civil history would be merged in natural history.  In strict logic it may be hard to object to this course, because no one can doubt that the rudiments and outlines of our own mental phenomena are traceable among the lower animals.  They have their economy and their polity, and if, as is always admitted, the polity of bees and the commonwealth of wolves fall within the purview of the biologist proper, it becomes hard to say why we should not include therein human affairs, which in so many cases resemble those of the bees in zealous getting, and are not without a certain parity in the proceedings of the wolves.  The real fact is that we biologists are a self-sacrificing people; and inasmuch as, on a moderate estimate, there are about a quarter of a million different species of animals and plants to know about already, we feel that we have more than sufficient territory.  There has been a sort of practical convention by which we give up to a different branch of science what Bacon and Hobbes would have called “Civil History.”  That branch of science has constituted itself under the head of Sociology.  I may use phraseology which, at present, will be well understood and say that we have allowed that province of Biology to become autonomous; but I should like you to recollect that that is a sacrifice, and that you should not be surprised if it occasionally happens that you see a biologist apparently trespassing in the region of philosophy or politics; or meddling with human education; because, after all, that is a part of his kingdom which he has only voluntarily forsaken.

Having now defined the meaning of the word Biology, and having indicated the general scope of Biological Science, I turn to my second question, which is—­Why should we study Biology?  Possibly the time may come when that will seem a very odd question.  That we, living creatures, should not feel a certain amount of interest in what it is that constitutes our life will eventually, under altered ideas of the fittest objects of human inquiry, appear to be a singular phenomenon; but, at present, judging by the practice of teachers and educators, Biology would seem to be a topic that does not concern us at all.  I propose to put before you a few considerations with which I dare say many will be familiar already, but which will suffice to show—­not fully, because to demonstrate this point fully would take a great many lectures—­that there are some very good and substantial reasons why it may be advisable that we should know something about this branch of human learning.