To start, I'll point to Blavatsky's Collected Writings XII where she points to the colour system she used in the diagram of the book. I'm not sure if the colour system is identical to the one used within her esoteric group, or if it's specific to the written context. This would be an interesting point to discuss also.
If I understand correctly, Blavatsky's sequence of colours and principles here are based on metaphysical predominance. I assume this first of all means the natural sequence of the colours as seen in the natural phenomena of the rainbow, and secondly to the sequence of the principles in a metaphysical events within the cosmogenesis of our solar system. What the latter actually means is of interest here. To draw a point of comparison, when Ervast wrote about the elementary sequence of the human building up, didn't he start from Friday or was it Saturday? I presume the idea of Ervast's was somwhere within Lucifer falling in to the darkness of matter or the idea of Saturnian material principle being the oldest within us - the physical body being our oldest instrument of all the other bodies of a human being. But indeed, Ervast spoke of human bodies as instruments, and Blavatsky is obviously speaking of a metaphysical sequence of principles within the solar system. So what are those metaphysical reasons for the colour sequence and their correspondences to the metaphysical principles as they are in Blavatsky's system? Or how does these principles predominate each other? Is it believeable or well formulated colour system, above individual emphases, by your judgement? I've tried to formulate these reasons myself, but I'm still too much in the midst of it to share so I'd like to hear if anybody has atleast some input on the subject.Collected Writings XII, Instructions II wrote:In Diagram 2 as already stated therein, no notice need be taken of the numbers used in the left-hand column, as these refer only to the Hierarchies of the Colours and Sounds on the metaphysical plane, and are not the characteristic number of the human principles or of the planets. The human principles elude enumeration, be-cause each man differs from every other, just as no two blades of grass on the whole earth are absolutely alike. Numbering is here a question of spiritual progress and the natural predominance of one principle over another. With one man it may be Buddhi that stands as number one; with another, if he be a bestial sensualist, the Lower Manas. With one, the physical body, or perhaps Prāna (the life-principle) will be on the first and highest plane, as would be the case in an extremely healthy man, full of vitality; with another it may come as the sixth or even seventh downward.
In the end of the above sitation Blavatsky emphasises thus:
Collected Writings XII, Instructions II wrote:Again, the colours and metals corresponding to the planets and human principles, as will be observed, are not those known exoterically to modern Astrologers and Western Occultists.
There are also other systems, like the one Blavatsky criticizes in this same text (Instructions II) which according to her has one of its origin points within Assyrian astrology's geocentric vision. This is more or less the same system we see within many of the Western Occult traditions and Agrippa's Three Books of Occult Philosophy. There the colour correspondences to the Celestial Powers goes accordingly:
Moon - Silver-White
Mars - Red
Mercury - Blue
Jupiter - White, but as often Purple or Orange
Venus - Green or Yellow
Saturn - Black
Sun - Yellow-Golden
What kind of value do you see with the latter system personally or in a larger, universal or cultural context?