“Beauty is pleasure regarded as the quality of a thing.”
Santayana defines beauty as pleasure experienced as though it belonged to the perceived object, making aesthetic value depend on an appreciative response rather than a detached physical property.
Source details
The Sense of Beauty (1896), Part I, §11, ‘The definition of beauty,’ Project Gutenberg #26842; the represented section begins on printed page 49. ‘Beauty is pleasure regarded as the quality of a thing’ is Santayana’s summary definition after describing beauty as positive, intrinsic and objectified value. This remains historical naturalistic aesthetic theory / philosophical psychology, not a modern empirical test proving an object objectively beautiful.