The new method of definition which Socrates applied to problems of human conduct was extended by Plato to the whole universe of the knowable.
Religion may " feel," like Tennyson's " man in wrath, " and may expatiate in an undefined awe; science alone is to possess the " knowable."
It appears, therefore, that Spencer ultimately describes the Knowable in terms of the mechanical conceptions of matter and motion, and that this must give a materialistic colouring to his philosophy.
Aristotle emphasized being as being, without always sufficiently asking whether the things whose existence he asserted are really knowable.