Is there a term I can use to refer to this quote from a poem?

I am writing a biography. The woman I am writing about lost her father to suicide when she was 14. She later quoted a poem that she said embodied her understanding of his wish for her to "make harbour" in his name. The quote:

A shipwrecked sailor buried on this coast,
Bids you set sail.
Full many a gallant ship
When we were lost,
Weathered the gale.

(It is a translated quote from an unknown Greek poet which she may have read in Pragmatism by William James.)

Is there a word I can use to refer to the quote? It was her guiding light, so, rather than just refer to it as a "quotation" or "poetry fragment", I’d prefer a word or a term that is more specific if there is one.

Those few lines were her _______.