alchemical · from c. 1530
The Three Principles
Sulphur, salt and mercury — the three signs Paracelsus put underneath the seven planetary metals as the components everything else is made of.
What the sources claim for it
The three behaviours matter shows under heat: what burns, what flies off, and what stays.
History
Where does the Three Principles come from?
Medieval Latin alchemy already worked with sulphur and mercury as the two principles of metals. Paracelsus adds salt in the early sixteenth century, giving a triad: sulphur for what burns, mercury for what is fluid and volatile, salt for what remains as ash. Each has its own sign, and the signs are used in manuscripts and printed books as notation rather than as emblems.
The move matters because it is the point at which alchemical notation stops being purely astrological. The planetary signs name substances by which planet governs them; the tria prima names them by how they behave under fire, which is an argument about matter rather than about correspondence.
Afterwards
What did it turn into?
Absorbed into the standardised chemical symbol tables of the seventeenth and eighteenth centuries and then discarded, along with the rest of alchemical notation, once Berzelius introduced letter symbols in 1813.
Which texts describe it?
None, and here is why
Waiting on Paracelsus. The three principles are his formulation and are set out across his medical and alchemical works, none of which this corpus carries. The mark is described here from the doctrine rather than from a passage, and the page says so rather than implying a citation exists.
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