We have seen how the pre-Socratic philosophy ended in the Sophists; we have now to see how the post-Socratic ended in the Sceptics. Again was repeated the same result exhibited in former times, that the doctrines of the different schools, even those supposed to be matters of absolute demonstration, were not only essentially different, but in contradiction to one another. Again, therefore, the opinion was resumed that the intellect of man possesses no criterion of truth, being neither able to distinguish among the contradictions of the impressions of the senses, nor to judge of the correctness of philosophical deductions, nor even to determine the intrinsic morality of acts. And, if there be no criterion of truth, there can be no certain ground of science, and there remains nothing for us but doubt. Such was the conclusion to which Pyrrho, the founder of the Sceptics, came. He lived about B.C. 300. His philosophical doctrine of the necessity of suspending or refusing our assent from want of a criterion of judgment led by a natural transition to the moral doctrine that virtue and happiness consist in perfect quiescence or freedom from all mental perturbation. This doctrine, it is said, he had learned in India from the Brahmans, whither he had been in the expedition of Alexander. On his return to Europe he taught these views in his school at Elis; but Greek philosophy, in its own order of advancement, was verging on the discovery of these conclusions. [Sidenote: Secondary analysis of ethical philosophy.] The Sceptical school was thus founded on the assertion that man can never ascertain the true among phenomena, and therefore can never know whether things are in accordance or discordance with their appearances, for the same object appears differently to us in different positions and at different times. Doubtless it also appears differently to various individuals. Among such appearances, how shall we select the true one, and, if we make a selection, how shall we be absolutely certain that we are right? Moreover, the properties we impute to things, such as colour, smell, taste, hardness, and the like, are dependent upon our senses; but we very well know that our senses are perpetually yielding to us contradictory indications, and it is in vain that we expect Reason to enable us to distinguish with correctness, or furnish us a criterion of the truth. The Sceptical school thus made use of the weapon which the Sophists had so destructively employed, directing it, however, chiefly against ethics. But let us ascend a step higher. If we rely upon Reason, how do we know that Reason itself is trustworthy? Do we not want some criterion for it? And, even if such a criterion existed, must we not have for it, in its turn, some higher criterion? The Sceptic thus justified his assertion that to man there is no criterion of truth. [Sidenote: The doctrines of Pyrrho.] [Sidenote: No certainty in knowledge.]