Perhaps psychologically, sympathy pains allow the man to go through the pain with the woman, so she doesn't have to do it alone. According to one article I unearthed on the subject, though, there is a biological foundation for these feelings. Men with pregnant partners were shown to have an increased level of estrogen and a decreased level of testosterone in one test.
William Blake (1757-1827) , English artist, mystic and poet wrote Songs of Innocence (1789): a poetry collection written from the child s point of view, of innocent wonderment and spontaneity in natural settings which includes Little Boy Lost, Little Boy Found and The Lamb;
9-16). Trying to discuss Blake's point in writing The Tyger requires that we understand Blake's intention in composing the poem, and we can only guess at a poet's intention--unless we have his own statement about why he wrote a particular poem.