When someone suffers the loss of a person whom they love, there is always a certain wonder, and even resentment, that the world seems not to notice. The heavens do not open, the sun still shines, and most people go about their business as if nothing monumental had happened.
That is one of the reasons we observe shiva, the seven days of mourning. The avel, the one who mourns, wears torn clothes except on Shabbat so that everyone knows that for this person the world has been plunged into a kind of darkness and will never be the same. The word avel means withdrawal or solitude, because even in a crowd the one who grieves often feels separate and alone.
The tear represents the way in which a life has been torn in two, and reminds us of the wise words of the Kotzker Rebbe — the only whole heart is a broken one. To have one’s heart broken in this world is to prove that one has loved, and therefore that one’s heart is whole. Gradually the scarred heart will re-enter the world to help another with the gentleness and wisdom born of pain.