The trines are expressed in alchemy through the concepts of Salt, Sulfur, and Mercury. This is kinda like your Sunday morning trinity but expressed in a lower more chemical way, as if you could pour these into a beaker and form personal amalgams. The triangle moves us past the square – past the natural plane and the things we can witness with our 5 senses.
The square presented in the last module correlates to the physical universe. With the triangle we don’t limit ourselves so much. The Sulphur and Mercurial aspects of the triangle include the non-physical aspects of the macrocosm and microcosm. It is the preferred system for approaching any alchemy that extends beyond practical scientific experiments on the material world.
Maier tells us that the triangle represents the tria prima of salt, sulfur, and mercury. It also represents the three colour stages of the alchemical magnum opus with the outer triangle representing the final stage of rubedo.
“In the same way the Philosophers want the square to be changed into a triangle, that is to say in body, spirit, and soul, the three of which appear in three colours preceding the red colour, namely the body or the earth appears in the black colour of Saturn, the spirit as if it were the water, appears in the whiteness of the moon, and the soul, or the air, appears in the yellow colour of the sun. With that the triangle is completed.” – Atalanta Fugiens Emblem 21.
The three Principles of things are produced out of the four elements in the following manner: Nature, whose power is in her obedience to the Will of God, ordained from the very beginning, that the four elements should incessantly act on one another, so, in obedience to her behest, fire began to act on air, and produle, that ced Sulphur; air acted on water and produced Mercury; water, by its action on earth, produced Salt. Earth,
alone, having nothing to act upon, did not produce anything, but became the nurse, or womb, of these three Principles. We designedly speak of three Principles; for though the Ancients mention only two, it is clear that they omitted the third (Salt), not from ignorance…
When we do a little mix and match of these three substances we can express them in terms of the 7 classical planets. The seven heavens take the concept of our alchemical trinity and start to form it into a master plan. The threes describe the mountaineers. The sevens describe the ascent. Take a look at the caduceus and the symbols we use for the planets.