The intelligence is like the sun, which does not illuminate space if there is no object from which its rays are reflected.
 Arthur Schopenhauer, The World as Will and Representation (1819). copy citation

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Author Arthur Schopenhauer
Source The World as Will and Representation
Topic intelligence sun
Date 1819
Language English
Reference
Note Translated by R. B. Haldane and J. Kemp
Weblink http://www.gutenberg.org/files/40097/40097-h/40097-h.html

Context

“As there can be no object without a subject, so also there can be no subject without an object, i.e., no knower without something different from it which is known. Therefore a consciousness which is through and through pure intelligence is impossible. The intelligence is like the sun, which does not illuminate space if there is no object from which its rays are reflected. The knower himself, as such, cannot be known; otherwise he would be the known of another knower. But now, as the known in self-consciousness we find exclusively the will. For not merely willing and purposing in the narrowest sense, but also all striving, wishing, shunning, hoping, fearing, loving, hating, in short, all that directly constitutes our own weal and woe, desire and aversion, is clearly only affection of the will, is a moving, a modification of willing and not-willing, is just that which, if it takes outward effect, exhibits itself as an act of will proper.31 In all knowledge, however, the known is first” source