Outer, Inner and Other

Kalachakra is organised around a correspondence in three registers, and the tradition names them plainly. The outer wheel is the cosmos: its structure, its measurements and the cycles of the heavens. The inner wheel is the human body: its channels, its winds and the rhythms of breath and of the lunar month within it. The third, which the texts call the other or the alternative wheel, is the practice, the mandala and the deity through which the first two are worked upon.

The logic is that the outer and inner are the same system at two scales, so that operating on the body operates on the cosmos and the practice is what makes the operation possible. The tantra develops this at unusual length, which is why it is often described as the most systematic of the Indian Buddhist tantras rather than merely the last.

It is also the most self contained. The Kalachakra carries its own cosmology, its own astronomy and calendar and its own account of the kingdom of Shambhala and its line of kings, material that other tantras leave to separate literatures. David Snellgrove's survey of Indo Tibetan Buddhism and John Powers's introduction to Tibetan Buddhism both set it in relation to the wider tantric corpus, where its distinctiveness on all three counts is what stands out.