Ovid's interpritation, in my opinion is the best. Metamorphosis
Narcissus' mother, after his birth went to the oracle Tiresias. He told her that her son would have and indefinate lifespan as long as he never knew himself. She kept him from ever seeing himself and in time he grew into a beautiful and strong boy. Several women as well as men would throw themselves at him trying to gain his affection, but he always remained disinterested. People would become so intranced by his beauty that when he was near they could see nothing but Narcissus.
One day he was hunting in the woods alone when Echo spotted him. She fell in love with him just like all of the others and, as he always did, he refused her. She chased him and he threatened her and so she went to a cave to sulk. She was so distraught that she sat on a rock in the cave and refused to move. She remained there and eventually her body began to waste away until there was nothing to her but rock and voice.
Meanwhile Narcissus went to rest himself at a nearby spring and when he bent to drink he saw his reflection and fell in love with himself. Apparently Narcissus was all looks and no brain because he didn't realize that the man he was looking at was himself. He began to beckon to his reflection and plead with it that he should become his own lover. Echo didn't make it any easier on him because every time he made an intreaty to himself, she would respond in his voice. When he said, "I love you", Echo said "I love you". And so he knew that his reflection wanted him as much as he did, but feared that something was seperating them, so he prayed to the gods to let them be together. He, like Echo, withered away, but the gods, hearing his pleas, took pity on him and turned him into an equally beautiful flower, the narcissus, that would always grow next to the spring so that he might always see himself...or his beloved.