Themes
Love against the soul
The Fisherman's refrain about his soul, 'I cannot see it. I may not touch it. I do not know it', shows how little he values what he cannot hold. He gives it up for the Mermaid without a second thought, and twice turns down Wisdom and Riches with the words 'Love is better'. In the end love proves stronger than the Soul itself: it cannot enter his heart, 'so compassed about with love' is it, until the heart breaks 'through the fullness of his love' and the two become one again.
A soul without a heart
The Soul begs, 'give me thy heart, for the world is very cruel, and I am afraid', and is refused. The result is the tale's darkest turn. Sent into the world with no heart, the Soul lies, threatens and steals, and when it returns it leads the Fisherman into theft, cruelty and violence. Its explanation is simple: 'thou gavest me no heart, so I learned to do all these things and love them.' The tale suggests that a soul cut off from love becomes evil.
Wisdom, riches and desire
The Soul's three temptations are carefully ranked. The Mirror of Wisdom, which reflects everything except the face of the one who looks into it, and the Ring of Riches, taken from a frightened Emperor, leave the Fisherman unmoved. What brings him back is a girl whose naked feet move over a carpet 'like little white pigeons', because the Mermaid has no feet and cannot dance. He can refuse the greatest goods of the mind and the world, but not a sudden desire of the body.
Harsh faith and the God of Love
The Priest calls the love of the body vile, curses the Fauns and the singers of the sea, and drives the Fisherman from his door. When he finds the drowned lovers he will not bless the sea, and orders them buried with no mark, 'that none may know the place of their resting'. Yet strange flowers from their grave trouble him until he preaches, without knowing why, of 'the God whose name is Love', and blesses the sea, the Fauns and all the wild things in God's world.
What a soul is worth
Everyone the Fisherman meets puts a different price on his soul. The Priest says it 'is worth all the gold that is in the world'. The merchants say it is 'not worth a clipped piece of silver' and offer to buy his body as a slave instead. The Witch, who can turn autumn leaves into gold, grows pale and shudders when she hears what he wants. The tale gives its own answer only at the end, when the Soul and the loving heart are united again in death.