I am a fan of Leonard Cohen and there is a part in the Anthem lyrics that means a lot:

There is a crack in everything
That’s how the light gets in.

In other words, we need to be open to let the light in – and to let our own light out.

Added in a comment by Sue James

Perhaps another way of expressing this can also be found in the words of another poet – Kahlil Gibran:

“Your pain is the breaking of the shell that encloses your understanding.
Even as the stone of the fruit must break, that its heart may stand in the sun, so must you know pain.”

This was originally posted at another (now extinct) blog of mine.