We must now consider further the method in which the Sceptics proceed, and it consists in this, that they have brought the universal principle that each definite assertion has to be set over against its ‘other,’ into certain forms, not propositions. Thus, in view of the nature of Scepticism, we cannot ask for any system of propositions, nor will this philosophy really be a system; just as little did it lie in the spirit of Scepticism to form a school, properly speaking, but only an external connection in the wider sense of the word. Sextus (Pyrrh. Hyp. I. c. 8, § 16, c. 3, § 7) hence says that Scepticism is no selection (αἵρεσις) of dogmas, it is not a preference for certain propositions, but only that which leads, or rather which directs us (ἀγωγή) to live rightly and think correctly; thus it is in this way rather a method or manner by which only universal modes of that opposition are shown. Now since what sort of thoughts reveal themselves is a matter of contingency, the manner and mode of grasping them is contingent likewise; for in one the contradiction appears thus and in another otherwise. These determinate modes of opposition, whereby the withholding of assent comes to pass, the Sceptics called tropes (τρόποι), which are turned upon everything that is thought and felt in order to show that this is not what it is implicitly, but only in relation to another—that it thus itself appears in another, and allows this other to appear in it, and consequently that, speaking generally, what is, only seems; and this, indeed, follows directly from the matter in itself, and not from another which is assumed as true. If, for example, men say that empiric science has no truth because truth exists only in reason, this is only assuming the opposite of empiricism; likewise the truth of reason proved in itself is not a refutation of empiric science, for this last stands alongside of the former with equal rights as, and within the same.