Mind is a fluid; the lights and shadows that flicker through it have no real boundaries, and no possibility of permanence.
 George Santayana, The Sense of Beauty (1896). copy citation

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Author George Santayana
Source The Sense of Beauty
Topic permanence shadow
Date 1896
Language English
Reference
Note
Weblink http://www.gutenberg.org/files/26842/26842-h/26842-h.htm

Context

“and we have chosen the familiar one of matter, form, and expression, as least likely to lead us into needless artificiality. But artificiality there must always be in the discursive description of anything given in consciousness. Psychology attempts what is perhaps impossible, namely, the anatomy of life. Mind is a fluid; the lights and shadows that flicker through it have no real boundaries, and no possibility of permanence. Our whole classification of mental facts is borrowed from the physical conditions or expressions of them. The very senses are distinguished because of the readiness with which we can isolate their outer organs.” source