Play:

"Play involves breaking rules. Playful play involves having fun while doing so."

"At the heart of play is the pleasure of engaging in the activity or thought process for its own sake, without any extrinsic reward."

"Play may therefore fulfil a probing role that enables the individual to escape from false endpoints, or local optima (Bateson, 2011)."

"In general, play is an indicator of psychological and physical well-being (Held & Spinka, 2011). It is usually the first activity to disappear if an individual is stressed, anxious, hungry or ill."

"playful behaviour and playful thought can generate radically new approaches to challenges set by the physical and social environment."

"Humorous people often behave playfully and playful people tend to have a good sense of humour."

"A large part of human play goes on in the mind and may not manifest itself in overt behaviour."

Play, Playfulness, Creativity and Innovation
Bateson & Martin