Though a survey of the idea itself of the good (agathon) may be of no service to the arts (techne), and for the common purposes of the merely animal life (zoe), yet we may say with Plato in the 7th book of his Republic, that “He who is not able by the exercise of his reasoning power (dianoia) to define the idea of the goody separating it from all other objects, and piercing, as in a battle, through every kind of argument; endeavouring to confute, not according to opinion (doxa), but according to essence (ousia), and proceeding through all the dialectical energies (dialektike) with an unshaken reason, is in the present life sunk in sleep, and conversant with the delusions of dreams (hypnos) ; and that before he is roused to a vigilant state, he will descend to Hades, and be overwhelmed with a sleep perfectly profound.”