4 ideas
Negative capability is the capacity to remain in uncertainties, mysteries and doubts without any irritable reaching after fact and reason. Keats identifies it as the quality that forms a person of achievement, especially in literature. He argues that the urge to close a question early sacrifices a fine perception grasped in half-knowledge for the false comfort of a system.
Keats rejects the view of the world as a 'vale of tears' from which one is rescued. He recasts it as a school in which raw intelligences become individual souls with identity. The mechanism is that a heart must feel and suffer in a thousand diverse ways, so pain and difficulty are the curriculum by which a self is formed, not obstacles to it.
Keats claims the poetical character has no identity of its own. It is continually filling some other body, taking as much delight in conceiving an Iago as an Imogen. Seen this way, the artist's absence of a fixed self and moral stance is what lets them fully inhabit others, the reverse of the 'egotistical sublime' poet who imposes his own personality on everything.
Keats holds that nothing becomes real until it is experienced. Even proverbs and philosophical axioms stay inert until life proves them on the pulse. Knowledge received as statement is therefore not yet knowledge, and understanding comes through lived sensation and feeling, not through assent to argument.