In Carl Jung's studies of alchemy, he believed the first record of an homunculus in alchemical literature appeared in the Visions of Zosimos, written in the third century AD, although the actual word "homunculus" was never used. In the visions, Zosimos mentions encountering a man who impales him with a sword, and then undergoes "unendurable torment," his eyes become blood, he spews forth his flesh, and changes into "the opposite of himself, into a mutilated anthroparion, and he tore his flesh with his own teeth, and sank into himself," which is a rather grotesque personification of the ouroboros, the dragon that bites its own tail, which represents the "dyophysite" nature in alchemy: the balance of two principles. Zosimos later encounters several other homunculi, named as the Brazen Man, the Leaden Man, and so forth. Commonly, the homunculi "submit themselves to unendurable torment" and undergo alchemical transformation. Zosimos made no mention of actually creating an artificial human, but rather used the concept of personifying inanimate metals to further explore alchemy.