(n.) The grievance complained of; the substantial cause of the action; also, in general, the ground or essence of a complaint. Bouvier.

axiom bench mark best part better part body bulk cardinal point center chief thing climax core cornerstone crisis critical point crux elixir essence essential essential matter flower focus fundamental generality gist great point heart high point hypostasis important thing inner essence issue kernel keystone landmark main body main point main thing major part majority marrow mass material point meat milestone most nub nucleus nuts and bolts pith pivot plurality postulate principle quid quiddity quintessence real issue salient point sap sine qua non soul spirit stuff substance substantive point the bottom line the nitty-gritty the point thrust turning point