Socrates devoted himself to the study of natural philosophy in his early years, but got nothing, so he came to the conclusion that natural philosophers have wrong views on philosophical objects, goals, ways and methods.
Philosophy cannot simply study nature without knowing useful personnel problems. Philosophy should study issues related to life, such as justice, virtue, courage and piety, instead of focusing on abstruse essence. Because nature is created by God, full of God's special will and purpose, and the object of God's wisdom, it is impossible for people to know it.
They don't care about themselves, they only care about nature, they are self-righteous, and they have different opinions on the origin of everything in the universe, based on sensory objects and based on natural objects. "They stare at things with their eyes, or try to grasp them with some sense." This method of sensory observation is not helpful, and so is the method of speculation.
The real reason and domination of all things in nature is not the origin of matter, but its inherent goodness. Because it is beyond our power to know the essence of nature, the real object of philosophy is not nature but man himself, that is, to know the goodness of man himself. Because of this, Cicero said that Socrates brought philosophy back from heaven to earth.
In a sense, Socrates' "knowing yourself" and protagoras's "knowing everything's scale" seem to have the same effect, both of which require people to turn their attention from nature to themselves.
However, protagoras understood man as an isolated special subject, so "man is the measure of everything" led to relativism; Socrates regards man as the rational thinking subject, and "knowing oneself" requires people to discover the common and universal essence of man.
The school of the wise abandoned the essence by emphasizing "man is the measure of all things", while Socrates reconstructed the essence by emphasizing "knowing oneself", but this essence, as a universal logos (definition), mainly refers to things in the spiritual and moral world.
His thoughts have always been confined to the field of moral practice. He was used to the practical action of social communication and did not put forward a complete theory of world outlook and ethics. Socrates' criticism reached a depth that the wise man's thought could not reach, and he excavated the principle of getting rid of the dilemma of natural philosophy, that is, the principle of taking the heart as the foundation.
He believes that there are some principles consistent with the origin of the world in people's minds, and advocates finding these internal principles in their minds first, and then stipulating the external world according to these principles.