Another(340) says: “It is stated in Aristotle’s _Metaphysics_(341) that Socrates introduced the method of Induction and Definition, which proceeds from the individual to the determination of the conception. Aristotle marks(342) the domain of ethics as that on which Socrates applied this method. According to him the fundamental view of Socrates was the indivisible unity of theoretical prudence and practical ability on ethical ground. Socrates conceived all the virtues to be prudences, inasmuch as they are sciences.(343) These statements are fully borne out by the portraits of Xenophon and Plato: Aristotle has only given point to their expression. Thus Xenophon says,(344) ‘he was ever conversing about human things, inquiring what was piety and what impiety; what honour and what turpitude; what just and what unjust; what sobermindedness and what madness; what courage and what cowardice; what policy and what politician; what the government of men and who capable of it; and suchlike things; and those who knew these he esteemed men of honour and goodness, those who knew them not to be justly called of servile mind.’ ‘Never did he cease inquiring with those who frequented him about what everything was.’(345) ‘And he did not distinguish between wisdom and temperance, but he asserted that justice and every other virtue was wisdom.’(346) With this view hang together the convictions that virtue can be taught, that all virtue in truth is only one, and that no one is willingly wicked, but only through ignorance.(347) The good is identical with the beautiful and the expedient. Right dealing, grounded upon prudence and practice, is better than good fortune. Self-knowledge, the fulfilment of the Delphic Apollo’s injunction, ‘Know thyself,’ is the condition of practical ability. External goods do not advance. To need nothing is godlike; to need the least possible comes nearest to the divine perfection.(348) Cicero’s well-known expression is substantially correct,(349) that Socrates called down philosophy from heaven to earth, introduced it into cities and houses, and required it to study life, morals, goods and evils, which constituted a progress from the natural philosophy pursued by his predecessors to ethics whose province is man. But Socrates possessed no complete system of ethical doctrines, but only the mainspring of inquiry; and so it was natural that he could only reach definite ethical statements in conversation with others. Thus his art was Mental Midwifery,(350) as Plato designates it. His confessed non-knowledge, resting on the firm consciousness of the essence of true knowledge, stood higher than the imagined knowledge of those who conversed with him; and to it was attached the Socratic Irony; that apparent recognition which is paid to the superior wisdom and prudence of another until this is dissolved into its nothingness by the dialectic examination which measures what is maintained as a generalisation by the fixed point of the particular case.