Borges, which Zlatko mentioned, comes first to my mind.
Second, perhaps rather oddly, is Nietzsche. His observations are normally considered aphorisms (see below), but I think looking at them may aide any writer concerned with succinctness, subtlety and profundity. See 'Human, All too Human' and 'The Gay Science'. Old Fred articulates in single lines what others have spent books masticating.
-m, who just watched the dog vomit on the rug
Main Entry: aph·o·rism
Etymology: Middle French aphorisme, from Late Latin aphorismus, from Greek aphorismos definition, aphorism, from aphorizein to define, from apo- + horizein to bound -- more at HORIZON
1 : a concise statement of a principle
2 : a terse formulation of a truth or sentiment : ADAGE