What is the mythological origin of word narcissism?

The word "narcissism" comes from the Greek myth of Narcissus. In the myth, Narcissus was a young man who was known for his beauty. He was so proud of his appearance that he would often spend hours admiring himself in a pool of water. One day, Narcissus fell in love with his reflection and refused to leave the pool. He became so obsessed with himself that he forgot to eat and drink, and eventually died. The myth of Narcissus is often used to describe someone who is excessively vain or self-absorbed.