You are the hands with which He is to bless men now.

I just found this quote attributed to St. Teresa of Avila in this book:

Christ has no body on earth but yours,
no hands but yours, no feet but yours,
Yours are the eyes through which is to look out
Christ's compassion to the world;
Yours are the feet with which he is to go about
doing good;
Yours are the hands with which he is to bless men now.