In the context of the Barasch essay:
Perhaps Thomas Aquinas was not so far off when he claimed, “No one becomes compassionate unless he suffers.” I take this less as a mandate for medieval masochism than an indecorous call to embrace our own authentic experience. If we’re not at home with the depth of our feelings, we’re likely to skirt the deep feelings of others.There are links to on-line texts of Aquinas here, but the quote doesn't not resolve to one of these sources; the translation doesn't seem to be on-line.