This is Narcissus seated at a brook. From Harbiye, second century AD.
From the Enc. Britt.: in Greek mythology, the son of the river god Cephissus and the nymph Leiriope; he was distinguished for his beauty. His mother was told that he would have a long life, provided he never looked upon his own features. His rejection, however, of the love of the nymph Echo or of his lover Ameinias drew upon him the vengeance of the gods. He fell in love with his own reflection in the waters of a spring and pined away (or killed himself); the flower that bears his name sprang up where he died. According to another source, Narcissus, to console himself for the death of his beloved twin sister, his exact counterpart, sat gazing into the spring to recall her features.
The story may have derived from the ancient Greek superstition that it was unlucky or even fatal to see one's own reflection.