The Walls Of Your Heart
You should be able to feel another person's pain in your heart – all the more so when many people are suffering. It is possible to know another person's pain and suffering yet still not feel them in your heart. When many people are suffering, you should certainly feel their pain in your heart. And if you do not feel it, you should knock your head against the wall: you should strike your head – your mind and intelligence – against the walls of your heart!
(Rebbe Nachman of Breslov)