“…and those who were subject to him, he treated with esteem and regard, as if they were his own children, while his subjects themselves respected cyrus as their "father" what other man but 'cyrus', after having overturned an empire, ever died with the title of "the father" from the people whom he had brought under his power? for it is plain fact that this is a name for one that bestows, rather than for one that takes away! ” –xenophon
the quote above, from an ancient greek historian, might have most accurately be said to have been inspired by

the persian king’s military cleverness
cyrus’ release of the jewish exiles and his providing them with funds to rebuild jerusalem
cyrus the great’s academic interests in the writings of jewish exiles
the upbringing of all persian young men, focusing on honesty and military strength.