VṚTRA, whose name is probably derived from the Sanskrit verbal root vṛ, meaning "hold back, restrain, envelop," is a serpent slain by Indra in the Ṛgveda. This act, which is Indra's most famous, most impoṛtant, and most frequently mentioned achievement, is the subject of several complete Ṛgvedic hymns (notably Ṛgveda 1.32 and 10.124). Vṛtra had coiled around a mountain, preventing the waters from flowing down; Indra pierced him with his thunderbolt and released the waters. This act has many symbolic resonances: slaying the dragon, releasing the waters or rains, bringing the ambrosial soma down from heaven or the mountains (an act that Indra is elsewhere said to accomplish by stealing it, on the back of an eagle), conquering the enemies of the invading Indo-Aryans (for Vṛtra is called a dāsa, or "slave," the name given to the...