“Alchemy is the science the object of which is the production of the philosopher’s stone, or the philosopher’s gold. . . .

There are seven stages, or processes, in the production of gold: calcination, putrefaction, solution, distillation, sublimation, conjunction and finally fixation. They produce, during the processes, and in their correct progression, the various colours which are proof that the experiment is proceeding satisfactorily. There are three main colours. First the black—the indication of dissolution and putrefaction—and when it appears it is a sign that the experiment is going well, that the calcination has had its proper effect of breaking down the various substances. Next comes the white, the colour of purification; and the third is the red, the colour of complete success. There are intermediary colours as well, passing through all the shades of the rainbow. Grey is the passage from black to white, yellow from wihte to red. Sometimes the gold is not produced even when the red appears, then . . . it moves on to green, remains there for a time and turns blue. Care must be taken at this point that it does not return to black, for then the process would have to be begun all over again. If success comes then the gold should appear after the blue, grains of philosopher’s gold. Sometimes the gold is in grains, but sometimes in liquid form, aurum potabile it is called, the elixir of long life. The whole process is sometimes described as the four ages, or the four seasons.”

—Enid Starkie, Arthur Rimbaud, 1961.