As everything in Nature has its forces and qualities, which react in a definite way when definitely affected, and constitute its character, man also has his character, from which the motives call forth his actions with necessity.
 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 action necessity
Date 1819
Language English
Reference
Note Translated by R. B. Haldane and J. Kemp
Weblink http://www.gutenberg.org/files/38427/38427-h/38427-h.html

Context

“But once there and existing, it has entered the chain of causes and effects, is always necessarily determined in it, and can, therefore, neither become something else, i.e., change itself, nor yet escape from the chain, i.e., vanish. Man, like every other part of Nature, is objectivity of the will; therefore all that has been said holds good of him. As everything in Nature has its forces and qualities, which react in a definite way when definitely affected, and constitute its character, man also has his character, from which the motives call forth his actions with necessity. In this manner of conduct his empirical character reveals itself, but in this again his intelligible character, the will in itself, whose determined phenomenon he is. But man is the most complete phenomenon of will, and, as we explained in the Second Book, he had to be enlightened with so high a degree of knowledge” source