Nature, fiction and imagination.
"Our imagination is stretched to the utmost, not, as in fiction, to imagine things which are not really there, but just to comprehend those things which are there."
— Richard Feynman
I hardly read fiction because reality is stranger and non-fiction more consistent with observations - and therefore more utile in governing behavior and predicting outcomes. Even the social constructs which comprise most fictional material are over-simplified and distorted.
Further, it seems that all of our attempts to IMPROVE on Nature are now backfiring, validating this thesis:
If you want to be the smartest person in the room, copy Nature!