I must warn the reader at the outset that the title of this chapter seems to promise a great deal more than he will find carried out in the chapter itself. To tell all that philosophy has meant in the past, and all that it means to various classes of men in the present, would be a task of no small magnitude, and one quite beyond the scope of such a volume as this. But it is not impossible to give within small compass a brief indication, at least, of what the word once signified, to show how its signification has undergone changes, and to point out to what sort of a discipline or group of disciplines educated men are apt to apply the word, notwithstanding their differences of opinion as to the truth or falsity of this or that particular doctrine.