The poetry of Jack Gilbert features somewhat heavily in The Heart is Not a Size.
Like Beth Kephart and the characters in The Heart is Not a Size, Jack Gilbert is from Pennsylvania originally, though he now lives in Berkeley, California.
The following is from his poem The Great Fires, you can read the whole poem on Poem Hunter:
Love lasts by not lasting.
Isaiah said each man walks in his own fire
for his sins. Love allows us to walk
in the sweet music of our particular heart.
Who are some of your favorite poets?