Whimsey
Part of speech: noun
Definition: A quaint and fanciful idea; a whim; playfully odd behaviour.
Notion
Part of speech: noun
Definition: Mental apprehension of whatever may be known or imagined; an idea; a conception; more properly, a general or universal conception, as distinguishable or definable by marks or notæ.A sentiment; an opinion.Sense; mind. Shakespeare.An invention; an ingenious device; a knickknack; as, Yankee notions.Inclination; intention; disposition; as, I have a notion to do it.
Example sentence: Yesterday I was thinking about the whole idea of genius and creative people, and the notion that if you create some magical art, somehow that exempts you from having to pay attention to the small things.