Add to this, that pity depends, in a great measure, on the contiguity, and even sight of the object; which is a proof, that ’tis deriv’d from the imagination.
There are many causes (“Add to this”) to pity and compassion, which Hume only partially enumerates; but #imagination appears to be the most important above all, which power and effects should not be underestimated. It is imagination that causes, “in a great measure” according to Hume, pity and compassion, since such passions arise even when there is no real harm:
[T]he imagination is affected by the general rule, and makes us conceive a lively idea of the passion, or rather feel the passion itself, in the same manner, as if the person were really actuated by it.
The sight of a weapon (a sword, for example) naturally produces a feeling of pity because of the harm such object can cause to others—even when nothing happens. Hume insists on the certainty of perception (the double relation of impressions and ideas, which keep coming back), however one cannot ignore the potentially misleading but nonetheless real effect of imagination on the passions.
A spectator of a tragedy passes thro’ a long train of grief, terror, indignation, and other affections, which the poet represents in the persons he introduces.
A story, although made of pure fiction, is enough to move us.
We are therefore (suspicious corollary) naturally compassionate.
Should we distrust passions deriving from such artificial causes, easily simulated?