The legend of Actaeon, from Bulfinch's Mythology:
It was midday, and the sun stood equally distant from either goal, when young Actaeon, son of King Cadmus, thus addressed the youths who with him were hunting the stag in the mountains.
"Friends, our nets and our weapons are wet with the blood of our victims; we have had sport enough for one day, and tomorrow we can renew our labors. Now, while Apollo parches the earth, let us put by our instruments and indulge ourselves with rest."
There was a valley thickly enclosed with cypresses and pines, sacred to the huntress-queen, Artemis. In the extremity of the valley was a cave, not adorned with art, but nature had counterfeited art in its construction, for she had turned the arch of its roof with stones as delicately fitted as if by the hand of man. A fountain burst out from one side, whose open basin was bounded by a grassy rim. Here the goddess of the woods used to come when weary with hunting and lave her virgin limbs in the sparkling water.
One day, having repaired thither with her nymphs, she handed her javelin, her quiver, and her bow to one, her robe to another, while a third unbound the sandals from her feet. Then Crocale, the most skilful of them, arranged her hair, and Nephele, Hyale, and the rest drew water in capacious urns. While the goddess was thus employed in the labors of the toilet, behold, Actaeon, having quitted his companions, and rambling without any especial object, came to the place, led thither by his destiny. As he presented himself at the entrance of the cave, the nymphs, seeing a man, screamed and rushed towards the goddess to hide her with their bodies. But she was taller than the rest, and overtopped them all by a head. Such a color as tinges the clouds at sunset or at dawn came over the countenance of Artemis thus taken by surprise. Surrounded as she was by her nymphs, she yet turned half away, and sought with a sudden impulse for her arrows. As they were not at hand, she dashed the water into the face of the intruder, adding these words: "Now go and tell, if you can, that you have seen Artemis unapparelled."
Immediately a pair of branching stag's horns grew out of his head, his neck gained in length, his ears grew sharp-pointed, his hands became feet, his arms long legs, his body was covered with a hairy spotted hide. Fear took the place of his former boldness, and the hero fled. He could not but admire his own speed; but when he saw his horns in the water, "Ah, wretched me!" he would have said, but no sound followed the effort. He groaned, and tears flowed down the face that had taken the place of his own. Yet his consciousness remained. What shall he do? Go home to seek the palace, or lie hid in the woods? The latter he was afraid, the former he was ashamed, to do. While he hesitated the dogs saw him. First Melampus, a Spartan dog, gave the signal with his bark, then Pamphagus, Dorceus, Lelaps, Theron, Nape, Tigris, and all the rest, rushed after him swifter than the wind. Over rocks and cliffs, through mountain gorges that seemed impracticable, he fled, and they followed. Where he had often chased the stag and cheered on his pack, his pack now chased him, cheered on by his own huntsmen. He longed to cry out, "I am Actaeon; recognize your master!" But the words came not at his will.
The air resounded with the bark of the dogs. Presently one fastened on his back, another seized his shoulder. While they held their master, the rest of the pack came up and buried their teeth in his flesh. He groaned, not in a human voice, yet certainly not in a stag's, and, falling on his knees, raised his eyes, and would have raised his arms in supplication, if he had had them. His friends and fellow-huntsmen cheered on the dogs, and looked every where for Actaeon, calling on him to join the sport. At the sound of his name, he turned his head, and heard them regret that he should be away. He earnestly wished he was. He would have been well pleased to see the exploits of his dogs, but to feel them was too much. They were all around him, rending and tearing; and it was not till they had torn his life out that the anger of Artemis was satisfied.
In the "Epic of Hades" there is a description of Actaeon and his change of form. Perhaps the most beautiful lines in it are when Actaeon, changed to a stag, first hears his own hounds and flees.
"But as I gazed, and careless turned and passed
Through the thick wood, forgetting what had been,
And thinking thoughts no longer, swift there came
A mortal terror; voices that I knew.
My own hounds' bayings that I loved before,
As with them often o'er the purple hills
I chased the flying hart from slope to slope,
Before the slow sun climbed the eastern peaks,
Until the swift sun smote the western plain;
Whom often I had cheered by voice and glance,
Whom often I had checked with hand and thong;
Grim followers, like the passions, firing me,
True servants, like the strong nerves, urging me
On many a fruitless chase, to find and take
Some too swift-fleeting beauty, faithful feet
And tongues, obedient always: these I knew
Clothed with a new-born force and vaster grown,
And stronger than their master; and I thought,
What if they tore me with their jaws, nor knew
That once I ruled them, brute pursuing brute,
And I the quarry? Then I turned and fled
If it was I indeed that feared and fled
Down the long glades, and through the tangled brakes,
Where scarce the sunlight pierced; fled on and on,
And panted, self-pursued. But evermore
The dissonant music which I knew so sweet,
When by the windy hills, the echoing vales
And whispering pines it rang; now far, now near
As from my rushing steed I leant and cheered
With voice and horn the chase; this brought to me
Fear of I knew not what, which bade me fly,
Fly always, fly; but when my heart stood still,
And all my limbs were stiffened as I fled,
Just as the white moon ghost-like climbed the sky,
Nearer they came and nearer, baying loud,
With bloodshot eyes and red jaws dripping foam;
And when I strove to check their savagery,
Speaking with words; no voice articulate came,
Only a dumb, low bleat. Then all the throng
Leapt swift upon me and tore me as I lay,
And left me man again."
Midst others of less note came one frail form,
A phantom among men; companionless
As the last cloud of an expiring storm,
Whose thunder is its knell; he, as I guess,
Had gazed on Nature's naked loveliness,
Actaeon-like, and now he fled astray
With feeble steps o'er the world's wilderness;
And his own Thoughts, along that rugged way,
Pursued like raging hounds their father and their prey.
Adonais, stanza 31.
The allusion is probably to Shelley himself.