No pre-Socratic philosopher, perhaps, has caused more disagreement, or been more variously interpreted, than Anaxagoras of Clazomenae. Among recent attempts to reconstruct his system some of the more notable are those of Tannery, Bailey, Cornford, Peck, and Vlastos. Each of these reconstructions, and especially that of Tannery, has its adherents; and since none of them (with the possible exceptions of the first and last) has much in common with any other, a universally acceptable solution to the fundamental problems involved may well by now seem unattainable. It is my belief, however, and it is the object of this paper to try to prove, that all these modern reconstructions have at least one quality in common, namely an undue complication. The actual system of Anaxagoras was, I believe, considerably simpler than any reconstruction yet forthcoming. Unfortunately what I take to be the basis of the whole system, Anaxagoras' reaction to his Eleatic predecessors, is by.no means easy to convey in brief and simple terms. But if I should succeed in conveying it, then it will, I hope, be seen in itself to possess such a simplicity and neatness that my contention will carry with it a fair warrant of its own truth. I shall, for convenience, divide my argument into ten sections, to which I shall append a brief summary of my conclusions.