Kilroy J. Oldster said this quote
“ Parallel to tenderness and cruelty, the cataracts of pleasure and pain are interrelated. Painful and pleasurable sensations instruct us of our physical boundaries. The collective scorecard of physical pain and pleasurable sensations define the evolving self. Our internal clockworks comprised of remembrances of times past, both painful and pleasurable, provide each of us with a telling emotional autobiography. What we primarily recall – pain or pleasure – is revelatory. How we act with kindness and tenderheartedly, or hardheartedly and cruelly is equally telling. ”