Who is Proteus from Selected Poems and what is their importance?

Proteus is Neptune's herdsmen. Neptune is the ancient Roman god of the sea. An old man and a prophet, Proteus is famed for his ability to change shapes, which explains Borges' fascination. The author often uses Proteus as a symbol or a metaphor for the changeability of things that nevertheless remain the same, like the effects of time, memory, and forgetting.