The lively idea of any object always approaches is impression; and it is certain we may feel sickness and pain from the mere force of imagination, and make a malady real by often thinking of it.
 David Hume, A Treatise of Human Nature (1738). copy citation

add
Author David Hume
Source A Treatise of Human Nature
Topic imagination pain
Date 1738
Language English
Reference
Note
Weblink http://www.gutenberg.org/files/4705/4705-h/4705-h.htm

Context

“And as this difference may be removed, in some measure, by a relation betwixt the impressions and ideas, it is no wonder an idea of a sentiment or passion, may by this means be inlivened as to become the very sentiment or passion. The lively idea of any object always approaches is impression; and it is certain we may feel sickness and pain from the mere force of imagination, and make a malady real by often thinking of it. But this is most remarkable in the opinions and affections; and it is there principally that a lively idea is converted into an impression. Our affections depend more upon ourselves, and the internal operations of the mind, than any other impressions;” source