That this story is not a mere invention, but rests on some mythological explanation of natural phenomena, I think more than probable, as it is found all over the world with few variations. As every Aryan branch retains the story, or traces of it, there can be no doubt that the belief in swan-maidens, who swam in the heavenly sea, and who sometimes became the wives of those fortunate men who managed to steal from them their feather dresses, formed an integral portion of the old mythological system of the Aryan family, before it was broken up into Indian, Persian, Greek, Latin, Russian, Scandinavian, Teutonic, and other races. But more, as the same myth is found. in tribes not Aryan, and far removed from contact with European or Indian superstition,—as, for instance, among Samoyeds and American Indians,—it is even possible that this story may be a tradition of the first primæval stock of men.
But it is time for me to leave the summer cirrus and turn to the tempest-born rain-cloud. It is represented in ancient Indian mythology by the Vritra or Râkshasas. At first the form of these dæmons was uncertain and obscure. Vritra is often used as an appellative for a cloud, and kabhanda, an old name for a rain-cloud, in later times became the name of a devil. Of Vritra, who envelopes the mountains with vapour, it is said, “The darkness stood retaining the water, the mountains lay in the belly of Vritra.” By degrees Vritra stood out more prominently as a dæmon, and he is described as a “devourer” of gigantic proportions. In the same way Râkshasas obtained corporeal form and individuality. He is a misshapen giant “like to a cloud,” with a red beard and red hair, with pointed protruding teeth, ready to lacerate and devour human flesh. His body is covered with coarse bristling hair, his huge mouth is open, he looks from side to side as he walks, lusting after the flesh and blood of men, to satisfy his raging hunger, and quench his consuming thirst. Towards nightfall his strength increases manifold. He can change his shape at will. He haunts the woods, and roams howling through the jungle; in short, he is to the Hindoo what the were-wolf is to the European.
A certain wood was haunted by a Râkschasa; he one day came across a Brahmin, and with a bound reached his shoulders, and clung to them, exclaiming, “Heh! go on with you!” And the Brahmin, quaking with fear, advanced with him. But when he observed that the feet of the Râkschasa were as delicate as the stamens of the lotus, he asked him, How is it that you have such weak and slender feet? The Râkschasa replied, “I never walk nor touch the earth with my feet. I have made a vow not to do so.” Presently they came to a large pond. Then the Râkschasa bade the Brahmin wait at the edge whilst he bathed and prayed to the gods. But the Brahmin thought: “As soon as these prayers and ablutions are over, he will tear me to pieces with his fangs and eat me. He has vowed not to walk; I will be off post haste!” so he ran away, and the Râkschasa dared not follow him for fear of breaking his VOW. (_Pantschatantra_, v. 13.) There is a similar story in the Mahâbhârata, xiii., and in the Kathâ Sarit Sâgara, v. 49-53.