Thus to hear the brave words and the bold defiance hurled out by the thinkers of the sixteenth and seventeenth centuries, one might fancy they, like Archimedes, sought a supernal vantage-ground from which they could move the world. Yet, unlike the material earth, the intellectual globe is a burden we each carry with us,--which we find upon us when--if ever--we begin to shake ourselves out of the slothful unconsciousness of our merely vegetative life. For though we all carry it, we do not all feel its weight. In some individuals and in some ages there is so accurate a proportion between the inner power and the outer pressure that the load of belief and custom is but a well-fitting garb, almost a second nature. To others there is a felt disproportion, a sense of superincumbent clothes and uncongenial, unnatural trappings. Out of such struggles to be free, grow, occasionally, philosophers, and reformers. To the former the burden is the burden of the unintelligible: to the latter the burden of the unbearable and intolerable. To the philosopher the removal of the burden consists in such a re-adjustment of the intellectual world that it shall be no longer a foreign thing, but bone of his bone and flesh of his flesh. But, to re-adjust and to re-organise, one must stand back from the objective: one must cast it forth, and look about for a clue to an exit from the maze of confusion. The given and subsistent is put on probation: not rejected, but for the moment declined: not denied, but asked to present its credentials.[1] This is the ἐποχή of the sceptical schools of later Greece; the invitation to doubt addressed by Descartes to his own soul. It is the protest against that vulgar precipitancy which in primitive and modern credulity is ready to give itself away to any doctrine which has the voice and the garb of outward authority. Or is it the assertion! of the royal and inalienable sovereignty of the Subjectivity to be _certain_ of whatever claims to be objective and _true_: the assertion that what is true must be seen and experienced to be true. Or it is, in another way, the principle of Socrates: that the beginning of knowledge, the first step in the way of wisdom, is to know that you know nothing--to realise the absolute supremacy of self-consciousness.