This search after a scientific basis for conduct was quite in the spirit of Socrates, but Plato seems to have set very little value on his master’s positive contributions to the systematisation of life. We have seen that the _Apologia_ is purely sceptical in its tendency; and we find a whole group of Dialogues, probably the earliest of Plato’s compositions, marked by the same negative, inconclusive tone. These are commonly spoken of as Socratic, and so no doubt they are in reference to the subjects discussed; but they would be more accurately described as an attempt to turn the Socratic method against its first originator. We know from another source that temperance, fortitude, and piety were the chief virtues inculcated and practised by Socrates; while friendship, if not strictly speaking a virtue, was equally with them one of his prime interests in life. It is clear that he considered them the most appropriate and remunerative subjects of philosophical discussion; that he could define their nature to his own satisfaction; and that he had, in fact, defined them as so many varieties of wisdom. Now, Plato has devoted a separate Dialogue to each of the conceptions in question,[119] and in each instance he represents Socrates, who is the principal spokesman, as professedly ignorant of the whole subject under discussion, offering no definition of his own (or at least none that he will stand by), but asking his interlocutors for theirs, and pulling it to pieces when it is given. We do, indeed, find a tendency to resolve the virtues into knowledge, and, so far, either to identify them with one another, or to carry them up into the unity of a higher idea. To this extent Plato follows in the footsteps of his master, but a result which had completely satisfied Socrates became the starting-point of a new investigation with his successor. If virtue is knowledge, it must be knowledge of what we most desire—of the good. Thus the original difficulty returns under another form, or rather we have merely restated it in different terms. For, to ask what is temperance or fortitude, is equivalent to asking what is its use. And this was so obvious to Socrates, that, apparently, he never thought of distinguishing between the two questions. But no sooner were they distinguished than his reduction of all morality to a single principle was shown to be illusive. For each specific virtue had been substituted the knowledge of a specific utility, and that was all. Unless the highest good were one, the means by which it was sought could not converge to a single point; nor, according to the new ideas, could their mastery come under the jurisdiction of a single art.