What does the phrase flitting life imply in apollo and hyacinthus

Apollo was passionately fond of a youth named Hyacinthus. He accompanied him in his sports, carried the nets when he went fishing, led the dogs when he went to hunt, followed him in his excursions1 in the mountains, and neglected for him his lyre2 and his arrows. One day they played a game of quoits3 together, and Apollo, heaving aloft the discus, 4 with strength mingled with skill, sent it high and far. Hyacinthus watched it as it flew and excited with the sport, ran forward to seize it, eager to make his throw, when the quoit bounded from the earth and stuck him in the forehead. He fainted and fell. The god, as pale as himself, raised him and tried all his art to stanch5 the wound and retain the flitting life, but all in vain; the hurt was past the power of medicine. Q1 As, when one has broken the stem of a lily in the garden, it hangs its head and turns its flowers to the earth, so the head of the dying boy, as if too heavy for his neck, fell over on his shoulder. "Thou diest, Hyacinth," so spoke Phoebus, 6 "robbed of thy youth by me. Thine is the suffering, mine the crime. Would that I could die for thee! But since that may not be thou shalt live with me in memory and in song. My lyre shall celebrate thee, my song shall tell thy fate, and thou shalt become a flower inscribed with my regret." While Apollo spoke, behold the blood which had flowed of hue more beautiful than the Tyrian7 sprang up, resembling the lily, if it were not that this is purple and that silvery white. 8 And this was not enough for Phoebus; but to confer still greater honor, he marked the petals with his sorrow, and inscribed "Ah! Ah!" upon them, as we see to this day. The flower bears the name of Hyacinthus, and with every returning spring revives the memory of his fate. Q2