A Treatise of Human Nature by David Hume — Read

It is remarkable, that the imagination and affections have close union together, and that nothing, which affects the former, can be entirely indifferent to the latter. Wherever our ideas of good or evil acquire a new vivacity, the passions become more violent; and keep pace with the imagination in all its variations. Whether this proceeds from the principle above-mentioned, that any attendant emotion is easily converted into the predominant, I shall not determine. It is sufficient for my present purpose, that we have many instances to confirm this influence of the imagination upon the passions.

Any pleasure, with which we are acquainted, affects us more than any other, which we own to be superior, but of whose nature we are wholly ignorant. Of the one we can form a particular and determinate idea: The other we conceive under the general notion of pleasure; and it is certain, that the more general and universal any of our ideas are, the less influence they have upon the imagination. A general idea, though it be nothing but a particular one considered in a certain view, is commonly more obscure; and that because no particular idea, by which we represent a general one, is ever fixed or determinate, but may easily be changed for other particular ones, which will serve equally in the representation.