The text does one thing, methodically. It ascends the subtle body and describes what is at each station. Muladhara at the base of the spine: four petals, a yellow square, the element earth, the seed syllable Lam. Svadhisthana: six petals, a white crescent, water, Vam. Manipura at the navel: ten petals, a red triangle, fire, Ram. Anahata at the heart: twelve petals, a smoke-coloured hexagram, air, Yam. Vishuddha at the throat: sixteen petals, a white circle, ether, Ham. Ajna between the brows: two petals, and the seed Om. Above them all, outside the series of six, the thousand-petalled sahasrara. Each centre also carries a presiding deity, a shakti, an animal vehicle and a set of Sanskrit letters on its petals.
The scheme is not a diagram of anatomy and the text does not present it as one. It is a map for a practice: the raising of kundalini, the coiled power at the base, up the central channel through each centre in turn to union in the sahasrara. The letters, the deities and the syllables are what the practitioner visualises and sounds at each stage, which is why the five bija mantras in this atlas point here as their source. Purnananda wrote it in Bengal in 1577, as the sixth chapter of a longer work, the Sri-tattva-cintamani; it is a late text summarising a much older tantric literature rather than an origin.