"Plato could not accept a philosophy destitute of spiritual aspirations; the two were at one with him. For the old Grecian sage there was a single object of attainment: real knowledge. He considered those only to be genuine philosophers, or students of truth, who possess the knowledge of the really-existing, in opposition to the mere seeming; of the always-existing, in opposition to the transitory; and of that which exists permanently, in opposition to that which waxes, wanes, and is developed and destroyed alternately."