It is the perception of meaning that is inexplicable yet somehow understandable. It usually reflects various aspects of one's life (including our emotions) or even existence as a whole in it's undefinable tenor. It is sort of like a vague realization of the hitherto unidentified complexity, interelatedness and pertinence of various forms and processes in life.

Apart from this I think universecannon has it on point with it being a thought that bypassed the mundane-transducing filters of our dysfunctional neural system. lol.