It is, perhaps, possible to conceive of animals or plants possessing souls, but the early alchemist attributed the same thing--or something kin to it--to metals also.

Furthermore, just as plants germinated from seeds, so metals were supposed to germinate also, and hence a constant growth of metals in the ground.

To prove this the alchemist cited cases where previously exhausted gold-mines were found, after a lapse of time, to contain fresh quantities of gold.

The "seed" of the remaining particles of gold had multiplied and increased.
But this germinating process could only take place under favorable conditions, just as the seed of a plant must have its proper surroundings before germinating; and it was believed that the action of the philosopher's stone was to hasten this process, as man may hasten the growth of plants by artificial means.

Gold was looked upon as the most perfect metal, and all other metals imperfect, because not yet "purified." By some alchemists they were regarded as lepers, who, when cured of their leprosy, would become gold.