The bare mention of this is sufficient.

Sympathy being nothing but a lively idea converted into an impression, it is evident, that, in considering the future possible or probable condition of any person, we may enter into it with so vivid a conception as to make it our own concern; and by that means be sensible of pains and pleasures, which neither belong to ourselves, nor at the present instant have any real existence.
But however we may look forward to the future in sympathizing with any person, the extending of our sympathy depends in a great measure upon our sense of his present condition.

It is a great effort of imagination, to form such lively ideas even of the present sentiments of others as to feel these very sentiments; but it is impossible we coued extend this sympathy to the future, without being aided by some circumstance in the present, which strikes upon us in a lively manner.

When the present misery of another has any strong influence upon me, the vivacity of the conception is not confined merely to its immediate object, but diffuses its influence over all the related ideas, and gives me a lively notion of all the circumstances of that person, whether past, present, or future; possible, probable or certain.

By means of this lively notion I am interested in them; take part with them; and feel a sympathetic motion in my breast, conformable to whatever I imagine in his.