20. His Conception of Philosophy. Philosophical Propedeutic. -- Philosophy is science par excellence (epistêmê). We reach its heights only by a series of initiations, which are so many successive steps or stages in knowledge

(1) The masses seek knowledge in the domain of sense, and virtue in conduct guided by those concrete sense-representations.

(2) But reflection soon convinces one that opinion, based on mere sense-perception, cannot lead to truth. To be guided by sensation, according to the Theaetetus, is to say with Protagoras that man is the measure of truth and falsehood, and, therefore, also of right and wrong: starting with such premisses, the Sophist is logical in his conclusions.

(3) To arrive at true science or philosophy, we must cast overboard the false principle which inspires common life and action, and seek for reality beyond the sense-world and outside it, that is, in the Idea. For opinion is only the shadow of science, just as the sense-world is but a shadow of the Ideal world (Republic, vii.). An irresistible impulse of our nature (erôs) urges us to rise above and beyond perishable things to the only true reality. It is the dialectic method (dialektikê methodos) that leads us to the contemplation of the Idea, by the process of forming and decomposing universal representations. Plato has traced and mapped out the lines of an education corresponding to this ladder of knowledge. Education commences by putting young people into contact with the sense-world by teaching them the arts, especially music and gymnastics. With the study of the natural sciences and of mathematics, they next learn how to detach themselves from the sense-world in order to arrive at the contemplation of the only true reality, the Idea. Philosophy is the final stage of education. Socrates, in the Euthydemus, calls it the royal art.

True morality is based upon the knowledge of the Idea. The "Good" is simply the Idea regarded as the term of the irresistible tendency of our being. Virtue is the love of that confused vision of the Absolute which in a former state we were contemplating face to face, and the insatiable desire to exchange this mortal life for immortality. Thus, philosophy, with Plato as with Socrates, embraces life in its entirety; it closely unites speculation and action without at the same time confounding them.