The Tattvas have long appeared to be the most unorthodox aspect of the Golden Dawn system, clashing quite obviously (at least on the surface) with the rest of the Order's Western-leaning teachings. The shapes and colours don't seem to fit, and it seems readily apparent to many that there are other, perhaps better, alternatives.
And here is where we need to be careful, because it is this kind of reasoning that can hold us back, can hinder us from actually learning something new. Not all is clean-cut on the esoteric path, and we are frequently forced to reconcile opposing ideas and balance seemingly contradictory thoughts.
First, let us explore the tattvas from a historical perspective. Many Golden Dawn members were also members of the early school of Theosophy when it was more Western focused. They were also exposed to Eastern teachings, some of which were mentioned in passing in various Golden Dawn documents, often as ways to help better explain Western material.
But why did the Golden Dawn use the tattvas and not other Eastern material? If it was simply an issue of them being new and intriguing, it begs the question why so many other new and intriguing ideas from across the globe were not embraced. Surely their introduction was less because of their general appeal and more because they actually fit into the system.
But how do they fit? Prithivi is a yellow square and relates to Earth. The square aspect matches Western associations, thanks to the Platonic solid of the cube, but the colour yellow would suggest, in the Golden Dawn, the element of Air. Likewise, the blue circle of Vayu would suggest Water, but is actually Air, and the black egg would suggest Earth, but is actually Spirit. Only the red triangle of Tejas appears to match other Golden Dawn associations, while the silver crescent of Apas does bring to mind the lunar connection of Water.
So then we have incongruence, and here is part of the beauty of this system within the carefully ordered material of the Golden Dawn. When these are skryed, the magician is instantly faced with, in most cases, preconceptions based on the colour and shape of the objects, which could easily provide a false vision. Yet because their real associations are often starkly different, it is generally easier to notice these illusions. For example, if the magician were to skry Prithivi and be greeted with Air-related imagery, then he or she immediately knows that the vision is not reliable. So, in a sense, the Tattvas provide an additional testing mechanism by the pure fact that they do not so easily match the correspondences Golden Dawn magicians have previously learned.
However, there is more to these than that. My personal experience suggests the Tattvas are tamer in nature than many other symbols, despite their elemental associations. They appear to cause less astral strain, and the energy involved is gentler than, for example, the four alchemical triangles that magicians in the West are more familiar with. The colours match more closely the Queen Scale, and thus work on a lower level than the King Scale colours we are perhaps more familiar with. Therefore, the Tattvas present a good introduction to the art of skrying that is less likely to result in dangerous situations for those new to the technique.
That raises the question why Mathers never advocated skrying the four elemental triangles. The Neophyte learns of these triangles, and they become an essential part of magical teaching and tradition. I agreed for many years with others who suggested these symbols were more appropriate, but I have come to learn differently over time. It was not like Mathers was not aware of them. They appear to be the most logical symbols to use, and yet he chose not to. There must be a reason for this apparent oversight.
The reason for this can be better understood when we look at the following passage in the original paper on the Hexagram Ritual:
"Remember also that the triangle if apex downward is an extremely evil and hurtful symbol and it is for this reason that these symbols of the elements [fire triangle, water triangle, air triangle, earth triangle] are not usually traced as Sigils, but are replaced with the Cherubic emblems of Leo, Scorpio, Aquarius and Taurus."
One will note that in the Lesser Ritual of the Hexagram the inverted triangle is only employed in conjunction with an upright triangle, unless in very rare circumstances as a double inverted triangle for use in workings with evil forces, largely beyond the scope of the Zelator Adeptus Minor.
What this reveals, however, is that the inverted triangle, employed as the symbol of Water, is considered evil, and thus also we may consider the inverted triangle with line employed as the symbol of Earth. Thus, if we were to skry these, we would be working with evil symbols. This would go a long way to explaining the harsher energy and more straining nature I have personally experienced with these symbols. It would also explain why these familiar symbols were not employed for skrying, with the Tattvas taking their place.
It is not difficult to see why Mathers advised against using an inverted triangle. The upright triangle is, after all, one of the primary symbols of the Order and that which we aspire to, the Supernal Triad. When inverted it is similar to the pentagram, putting Kether below Chokmah and Binah, and, in effect, marking the Fall. The symbols on the altar also relate to this, for while the inverted triangle is employed, the Cross is never placed below it, for that would be the symbol of the Order entirely overturned.
Of course, the Vault walls do employ the inverted Water triangle, but note that it is balanced by the upright Fire triangle, and between them is the reconciling symbol of Air. Note also the absence of the Earth Triangle, the very emblem of that which has Fallen.
There is much in this worth careful study, but this is sufficient for understanding the place of the Tattvas in the Golden Dawn system, and why also we should look deeper into why the pieces of the system were designed in this way.