Plato was admirably fitted for these sublime investigations by the possession of those moral qualities which were so prominent in the character of his master. He had that same deep seriousness of spirit, that earnestness and rectitude of purpose, that longing after truth, that inward sympathy with, and reverence for justice, and purity, and goodness, which dwelt in the heart of Socrates, and which constrained him to believe in their reality and permanence. He could not endure the thought that all ideas of right were arbitrary and factitious, that all knowledge was unreal, that truth was a delusion, and certainty a dream. The world of sense might be fleeting and delusive, but the voice of reason and conscience would not mislead the upright man. The opinions of individual men might vary, but the universal consciousness of the race could not prevaricate. However conflicting the opinions of men concerning beautiful things, right actions, and good sentiments, Plato was persuaded there are ideas of Order, and Right, and Good, which are universal, unchangeable, and eternal. Untruth, injustice, and wrong may endure for a day or two, perhaps for a century or two, but they can not always last; they must perish. The _just_ thing and the _true_ thing are the only enduring things; these are eternal. Plato had a sublime conviction that his mission was to draw the Athenian mind away from the fleeting, the transitory, and the uncertain, and lead them to the contemplation of an Eternal Truth, an Eternal Justice, an Eternal Beauty, all proceeding from and united in an Eternal Being--the ultimate ἀγαθόν--_the Supremely Good_. The knowledge of this "Supreme Good" he regarded as the highest science.[490] [Footnote 490: "Republic," bk. vi. ch. xvi. p. 193.]