The Song of Solomon is another name for the book called Song of Songs in the Bible (and the Torah). Ostensibly a love song by a man and a woman, following the process of a courtship, it is widely interpreted to be an allegorical celebration of the love between God and the Church (or the human soul). Some parts of the poem would have been considered shockingly explicit by a Victorian audience:
Your two breasts are like two fawns
that are twins of a roe,
which feed among the lilies.