The immensely influential philosopher-mathematician, mystic and sage, Pythagoras, believed that numbers were qualities that described not only the nature of the universe but also the nature of any system, including the human being. The mathematical model devised by Pythagoras is known as the Tetractys, one of the most deceptively simple and yet profound models that exists in the western tradition.  The Tetractys is a rich, many-layered symbol with a rich flow of meanings, relationships and correspondences. Simply expressed, the Pythagoreans believed that the nature of all things could be understood and described according to the powers of the one, the two, the three and the four as an unfolding sequence of creation. These numbers are not simply quantitative, but are also archetypes of number, with ‘oneness’, ‘twoness’, ‘threeness’ and ‘fourness’ being understood as wholes or unities in themselves, each with their own qualitative meaning.

The astrological chart is an exact representation of the Tetractys, being itself a unity, with each of the twelve signs of the zodiac being simultaneously polar (active or passive), modal (cardinal, fixed or mutable) and elemental (fire, earth, air, water). The number twelve is a remarkably complete number in which the polarity is repeated six times, the modes are repeated four times and the elements are repeated three times.

The Tetractys provides a useful model for the process of psychological development, which is remarkably similar to the various stages or processes recognised by the alchemists. Broadly speaking, the task is twofold. The initial task is to identify and differentiate each of the different levels since, as the alchemists repeatedly stated, ‘only separated things can unite’. Once the process of separation and differentiation has been achieved, the remaining task is to integrate all the different levels into a conscious unity and wholeness.