As a follow-up to my previous post:
Check out Mitra-Varuna, a 1940 essay in comparative Indo-European mythology by Georges Dumézil.
Here is a sample:
Though transformed into a band of supernatural beings, somewhat divine and somewhat demonic in character, called Gandharva, it can be recognized by one typical characteristic: men may join it by initiation. Moreover, just as the Luperci and the Lupercalis are mythically underwritten by the childhood, feral upbringing and early adventures of Romulus and Remus, so, too, the Gandharva educate heroes (Ayus, Arjuna and so on). In the Sg Veda the outward appearance of the (singular masculine) Gandharva is left vague, but in later writings the (masculine plural) Gandharva are beings with horses’ heads and men’s torsos who live in a special world of their own. As early as the hymns, moreover, they already stand in a precise relationship to horses and to the harnessing of chariots, those of the Sun and those of men alike, and they retain this feature throughout the epic literature. They are drinkers who steal the soma and other intoxicating drinks, who carry off women and nymphs (Apsaras), and who cheerfully live up to the ribald adjectives applied to them. Some ritual texts also claim that every woman’s first mate, before her husband, is a Gandharva. The initiation scene to which I just alluded is found in the touching legend of the two lovers Pliruravas and Urvasi. The earthly king Pururavas is united with the nymph Urvasi, who lives with him on the condition - as in the Psyche and Melusine stories - that he never show himself naked to her. The Gandharva, impatient to recover Urvasi come by night and steal the two lambs that she loves like children. Without taking time to dress, the king rushes out in pursuit, whereupon the Gandharva light up the sky with a flash of lightning. Urvasi sees her lover’s naked body, and she vanishes. Pururavas laments, so pitiably that in the end Urvasi allows him to find her. He meets her on the last night of the year (sarpvatsaratamlrp ratrim), and the next day the Gandharva grant him a wish. Upon Urvasi’s advice he chooses “to become one of the Gandharva.” The Gandharva then teach him a particular form of igneous sacrifice (the accessories of which are made from the wood of the asvattha tree, which contains the word asva, “horse,” in its name), which allows him to “become one of the Gandharva.” Furthermore, while among the Gandharva, Urvasi bears him a son named Ayus (literally, “vitality”).
Finally, is there any need to point to the numerous analogies, both in form and behavior, that link the Gandharva to the Greek centaurs? The centaurs have horses’ bodies and male human torsos; they are prodigius runners; they live in a land of their own, as wild as one can imagine ; they are great drinkers, sensual, ravishers of women (especially of young brides), and also include among their number at least some artists, scholars, and educators of heroes. In particular, Peleus, the beneficiary and victim, like Puriiravas, of a “melusinian” marriage, delivers his son, the young Achilles, to the centaur Chiron, who nurtures him for several years with the right amount of bone marrow and wisdom.