As a story in the Midrash puts it: A rich merchant was to marry the king's daughter.
Everything he gave her, however, was somehow inadequate and inappropriate–for she was born a princess–and he could never be rid of the feeling of obligation to her.
The soul too is a princess and can never be recompensed sufficiently.
It is a spark of the Divine, and no matter what one does or says or strives to accomplish, it is hardly ever enough.
Hence, the attribute of compassion is necessary to bridge the gap.
God hides Himself, even within the body of man, amidst all the body's grossness and problems.
His glory fills even the limited space of one's physical self.
At the same time, the Divine in us is the innocent one whom we compel to accompany us in our transgressions.
It is thus that He is deserving of pity.
This Divine spark in one needs to be redeemed, and the whole system of Torah and mitzvot may be considered a means to this end.
How shall I restore the Divine spark to its source?
How can I save the princess and bring her home?
–Rabbi Adin Steinsaltz
From The Long Shorter Way, Chapter 45, by Rabbi Adin Steinsaltz