Sri Aurobindo
Letters on Yoga
5. Planes and Parts of the Being
I never heard of two lotuses in the heart centre; but it is the seat of two powers, in front the higher vital or emotional being, behind and concealed the soul or psychic being.
The colours of the lotuses and the numbers of petals are respectively, from bottom to top:– (1) the Muladhara or physical consciousness centre, four petals, red; (2) the abdominal centre, six petals, deep purple red; (3) the navel centre, ten petals, violet; (4) the heart centre, twelve petals, golden pink; (5) the throat centre, sixteen petals, grey; (6) the forehead centre between the eye-brows, two petals, white; (7) the thousand-petalled 
lotus above the head, blue with gold light around. The functions are, according to our yoga,– (1) commanding the physical consciousness and the subconscient; (2) commanding the small vital movements, the little greeds, lusts, desires, the small sense-movements; (3) commanding the larger life-forces and the passions and larger desire-movements; (4) commanding the higher emotional being with the psychic deep behind it; (5) commanding expression and all externalisation of the mind movements and mental forces; (6) commanding thought, will, vision; (7) commanding the higher thinking mind and the illumined mind and opening upwards to the intuition and overmind. The seventh is sometimes or by some identified with the brain, but that is an error – the brain is only a channel of communication situated between the thousand-petalled and the forehead centre. The former is sometimes called the void centre, śūnya, either because it is not in the body, but in the apparent void above or because rising above the head one enters first into the silence of the self or spiritual being.
Current publication:
Sri Aurobindo. Letters on Yoga // SABCL.- Volume 22. (≈ 28 vol. of CWSA).- Pondicherry: Sri Aurobindo Ashram, 1971.- 502 p.
Other publications:
1. 10227.
Sri Aurobindo. Letters on Yoga. I // CWSA.- Volume 28. (≈ 22 vol. of SABCL).- Pondicherry: Sri Aurobindo Ashram, 2012.- 590 p.
2. 22831.
Sri Aurobindo. More Lights on Yoga [: Extracts from letters].– First Edition.– Pondicherry: Sri Aurobindo Ashram, 1948.– 141p.