The sentence of the oracle was clear, he told Socrates that he was the wisest of all men because he knew he did not know, and no doubt, that would be the first step towards getting to know. The legendary anecdote is indeed one of the most universal emblems of Western philosophical wisdom.
Socrates lived in the fifth century BC and his oral teaching was documented by his disciple Plato who told everything we can know about him today. Anthropological and ethical issues were his main concerns and he developed a particular method: the mayeutics. The majeutics was the art of giving birth for the purpose of forming the disciple:
My art is, in general, like that of midwives, the only difference is that my patients are men, not women and that my treatment is not with the body but with the soul, who is in the trance of giving birth (...) Some of those who frequent my company seem at first very unintelligent; but as we move forward in our discussions, all those who are favored by heaven make progress at such a rate that it is surprising to others and themselves, although it is clear that they have never learned anything from me: the numerous and admirable truths that give birth have discovered them for themselves. (Plato )