Anna Laetitia Barbauld was inquiring into –

“Those Kinds of Distress Which Excite Agreeable Sensations,”

 in which she had analyzed the emotion of pity into its constituents of – love, sympathy with pain, and the pleasure of feeling imaginary sorrow…”

“The pleasure of feeling imaginary sorrow”, how that struck me!       I think the way she uses the word "imaginary" is not exactly as we use it, I think that she simply means they are real emotions that we feel, and may indeed be very close to those of the sufferer, but the suffering isn't ours, it's imaginary, we, through compassion, imagine their hurt.

I read it over a number of times, and it reminded me of what could almost be called an echo by Henry Ward Beecher –

“Pity is a state of kindness excited by the site of suffering.” 

 I have always felt the emotions one feels when sympathizing with a sufferer a very difficult thing to describe. The situations can be so grim but in the midst of it is a longing to be where the suffering abide. 

When I read this quote "a state of kindness" it seemed so clear to me. Suffering humanity draws out, compels us, to do something kind to that suffering person. And in so doing, we experience a pleasure that loving sympathy produces in us.