4.] afterwards.
All these relations, when united together, convey the impression or consciousness of our own person to the idea of the sentiments or passions of others, and makes us conceive them in the strongest and most lively manner.
It has been remarked in the beginning of this treatise, that all ideas are borrowed from impressions, and that these two kinds of perceptions differ only in the degrees of force and vivacity, with which they strike upon the soul.

The component part of ideas and impressions are precisely alike.

The manner and order of their appearance may be the same.

The different degrees of their force and vivacity are, therefore, the only particulars, that distinguish them: 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.