If the boundaries of the self are defined by what we feel, then those who cannot feel even for themselves shrink within their own boundaries, while those who feel for others are enlarged, and those who feel compassion for all beings must be boundless. 
They are not separate, not alone, not lonely, not vulnerable in the same way as those of us stranded in the islands of ourselves, but they are vulnerable in other ways. 
Still, that sense of the dangers in feeling for others is so compelling that many withdraw, and develop elaborate stories to justify withdrawal, and then forget that they have shrunk. 
Most of us do, in one way or another.

- Rebecca Solnit