the choicest or most essential or most vital part of some idea or experience(noun.cognition)
Example:
The gist of the prosecutor's argument.
Synonym:center,
centre,
core,
essence,
heart,
heart and soul,
inwardness,
kernel,
marrow,
meat,
nitty-gritty,
nub,
pith,
substance,
sum
source: wordnet30