From the opening page, Chapter 1, of Diane Ackerman's book, Deep Play.

DEEP

adj. - 1. The most intense or extreme part. 2. Profoundly absorbed or immersed. 3. A distance estimated in fathoms.

- The American Heritage Dictionary of the English Language, 3rd edition

PLAY

It is an activity which proceeds within certain limits of time and space, in a visible order, according to rules freely accepted, and outside the sphere of necessity or material utility. The play-mood is one of rapture and enthusiasm, and is sacred or festive in accordance with the occasion. A feeling of exaltation and tension accompanies the action.

- Johan Huizinga, Homo Ludens

DEEP PLAY

1. A state of unselfconscious engagement with our surroundings. 2. An exalted zone of transcendence over time. 3. A state of optimal creative capacity.