This text is from Crowley's Book of Thoth.
The Princess of Cups represents the earthy part of Water; in particular, the faculty of crystallization. She represents the power of Water to give substance to idea, to support life, and to form the basis of chemical combination. She is represented as a dancing figure, robed in a flowing garment on whose edges crystals are seen to form.
For her crest she wears a swan with open wings. The symbolism of this swan reminds one of the swan in oriental philosophy which is the word AUM or AUMGN, which is the symbol of the entire process of creation.[1]
She bears a covered cup from which issues a tortoise. This is again the tortoise which in Hindu philosophy supports the elephant on whose back is the Universe. She is dancing upon a foaming sea in which disports himself a dolphin, the royal fish, which symbolizes the power of Creation.
The character of the Princess is infinitely gracious. All sweetness, all voluptuousness, gentleness, kindness and tenderness are in her character. She lives in the world of Romance, in the perpetual dream of rapture. On a superficial examination she might be thought selfish and indolent, but this is a quite false impression; silently and effortlessly she goes about her work.
In the Yi King, the earthy part of Water is represented by the 41st Hexagram, Sun. This means diminution, the dissolution of all solidity. People described by this card are very dependent on others, but at the same time helpful to them. Rarely, at the best, are they of individual importance. As helpmeets, they are unsurpassed.