These are difficulties which Teichmüller has, no doubt, fully weighed and put aside as not sufficiently strong to invalidate his conclusions. I have stated them in order to show that enough can be said for the old view to justify the republication of what was written on the assumption of its unquestionable truth. Moreover, researches conducted with so much skill and learning as those of Teichmüller demand some public acknowledgment in a work like the present, even when the results are such that the writer cannot see his way to accepting them as satisfactorily made out. There are many English scholars more competent than I am to discuss the whole question at issue. Perhaps these lines may induce some of them to give it the attention which it merits, but which, in England at least, it does not seem to have as yet received. My obligations to other writers have been acknowledged throughout this work, so far as I was conscious of them, and so far as they could be defined by reference to specific points. I take the present opportunity for mentioning in a more general way the valuable assistance which I have derived from Schwegler’s _Geschichte der Griechischen Philosophie_, Lange’s _Geschichte des Materialismus_, and Dühring’s _Geschichte der Philosophie_. The parallel between Socrates, Giordano Bruno, and Spinoza was probably suggested to me by Dühring, as also were some points in my characterisation of Aristotle. As my view of the position occupied by Lucretius with respect to religion and philosophy differs in many important points from that of Prof. Sellar, it is the more incumbent on me to state that, but for a perusal of Prof. Sellar’s eloquent and sympathetic chapters on the great Epicurean poet, my own estimate of his genius would certainly not have been written in its present form and would probably not have been written at all. On the whole, I am afraid that my acquaintance with the modern literature of the subject will be found rather limited for an undertaking like the present. But I do not think that wider reading in that direction would have much furthered the object I had in view. That object has been to exhibit the principal ideas of Greek philosophy in the closest possible connexion with the characters of their authors, with each other, with their developments in modern speculation, with the parallel tendencies of literature and art, with the history of religion, of physical science, and of civilisation as a whole. To interpret all things by a system of universal references is the method of philosophy; when applied to a series of events this method is the philosophy of history; when the events are ideas, it is the philosophy of philosophy itself. CONTENTS OF THE FIRST VOLUME. CHAPTER I. EARLY GREEK THOUGHT pages 1-52