Heraclitus and Plato, retire into solitude but placed himself before the very public, whose exulting admiration of Homer, whose passionate propensity for the honours of the gymnastic festivals, whose adoration of stones in human shape, he criticised severely with wrath and scorn, yet not as a brawling Thersites. The freedom of the individual was with him on its zenith; and by this almost limitless stepping free from all conventions he was more closely related to Parmenides than by that last divine unity, which once he had beheld, in a visionary state worthy of that century. His unity scarcely had expression and word in common with the one "Being" of Parmenides, and certainly had not the same origin. It was rather an opposite state of mind in which Parmenides found his doctrine of "Being," On that day and in that state he examined his two co-operating antitheses, the "Existent" and the "Non-Existent," the positive and the negative qualities, of which Desire and Hatred constitute the world and the Becoming. He was suddenly caught up, mistrusting, by the idea of negative quality, of the "Non-Existent." For can something which does not exist be a quality? or to put the question in a broader sense: can anything indeed which does not exist, exist? The only form of knowledge in which we at once put unconditional trust and the disapproval of which amounts to madness, is the tautology A = A. But this very tautological knowledge called inexorably to him: what does not exist, exists not! What is, is! Suddenly he feels upon his life the load of an enormous logical sin; for had he not always without hesitation assumed that _there were existing_ negative qualities, in short a "Non-Existent," that therefore, to express it by a formula, A = Not-A, which indeed could only be advanced by the most out and out perversity of thinking. It is true, as he recollected, the whole great mass of men judge with the same perversity; he himself has only participated in the general crime against logic. But the same moment which charges him with this crime surrounds him with the light of the glory of an invention, he has found, apart from all human illusion, a principle, the key to the world-secret, he now descends into the abyss of things, guided by the firm and fearful hand of the tautological truth as to "Being."