Alchemy was a science of the soul that’s why the images of the sea, sea creatures and fish appear frequently. In occult symbolism the sea has always been an image of the soul or spirit.The fishtail in occult images is usually a sign of the initiate. The image of the siren is usually intended to indicate a state in which the alchemist has reached the point of breaking through into the other world. The story of Jonah being swallowed by a large fish can be explained as a man who gives up his own lower personality, dies to the world and is then reborn into the world as a new man. This rebirth of soul was the main goal of the alchemists. The water is a symbol of a higher level of consciousness, the Quintessence.