gist

(noun) the central meaning or theme of a speech or literary work. Synonyms: effect, essence, burden, core.

(noun) the choicest or most essential or most vital part of some idea or experience. Synonyms: kernel, substance, core, center, centre, essence, heart, heart and soul, inwardness, marrow, meat, nub, pith, sum, nitty-gritty. Examples: "The gist of the prosecutor's argument." "The heart and soul of the republican party." "The nub of the story."