The intellect becomes tired; the will is never tired.
 Arthur Schopenhauer, The World as Will and Representation (1819). copy citation

add
Author Arthur Schopenhauer
Source The World as Will and Representation
Topic intellect
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

“It therefore requires the deed to convince us ourselves of the sincerity of the purpose. All these facts prove the absolute difference of the will and the intellect, the primacy of the former and the subordinate position of the latter. 4. The intellect becomes tired; the will is never tired. After sustained work with the head we feel the tiredness of the brain, just like that of the arm after sustained bodily work. All knowing is accompanied with effort; willing, on the contrary, is our very nature, whose manifestations take place without any weariness and entirely of their own accord.” source