writings of Cicero, the only record of the Sceptical opinions which we possess is the work of Sextus Empiricus, a physician who lived in the first half of the third century of the Christian era, that is to say, several centuries after Pyrrho and his followers. Sextus, however, must have had access to sufficient sources of information, for his compilation is ample, and appears to give a faithful and authentic expression to the opinions which it registers. It is an immense repository of doubts. Part of the work is entitled 'Outlines of Pyrrhonism, or Sceptical Commentaries.' The other part is entitled 'Disputations against the Mathematicians.' It is an attack on all positive or dogmatic philosophy. Sextus was himself an advocate of the opinions which he recorded.
9. The principle on which the Pyrrhonic Scepticism, as expounded by Sextus, is founded, is the relativity of all knowledge, feeling, and sensation, the relativity of all truth, sensible, moral, and intellectual. Scepticism is in fact merely a more fully developed, more systematic, and more thoroughgoing Sophistic. Substantially the Sceptics added but little to the maxim which expresses the relativity of all human cognition, that man is the measure of the universe; but they carried out this maxim into a multiplicity of directions and details, and enforced it with abundant and superabundant illustrations. They dwelt more than the Sophists had done on the uncertainty and utter ignorance as to objective and inde-
