Now, if we imagine twenty-one cards disposed in the shape of a triangle, seven cards on each side, a point in the centre of the triangle represented by the zero card, and a square round the triangle (the square consisting of fifty-six cards, fourteen on each side), we shall have a representation of the relation between God, Man and the Universe, or the relation between the world of ideas, the consciousness of man and the physical world.
The triangle is God (the Trinity) or the world of ideas, or the noumenal world. The point is man's soul. The square is the visible, physical or phenomenal world. Potentially, the point is equal to the square, which means that all the visible world is contained in man's consciousness, is created in man's soul. And the soul itself is a point having no dimension in the world of the spirit, symbolized by the triangle. It is clear that such an idea could not have originated with ignorant people and clear also that the Tarot is something more than a pack of playing or fortune-telling cards.
(From The Symbolism of the Tarot by P. D. Ouspensky)