Our affections depend more upon ourselves, and the internal operations of the mind, than any other impressions; for which reason they arise more naturally from the imagination, and from every lively idea we form of them.
 David Hume, A Treatise of Human Nature (1738). copy citation

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

Context

“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; for which reason they arise more naturally from the imagination, and from every lively idea we form of them. This is the nature and cause of sympathy; and it is after this manner we enter so deep into the opinions and affections of others, whenever we discover them.
What is principally remarkable in this whole affair is the strong confirmation these phaenomena give to the foregoing system concerning the understanding, and consequently to the present one concerning the passions; since these are analogous to each other.” source