Ronald Davidson: "Why are there mantras in Buddhism?"
Phrases designated as ‘mantra’ or ‘vidyā’ have been employed by Buddhists at least since the beginning of the common era, but the circumstances of their inclusion in Buddhist ritual activities have been poorly explored. Certainly, phrases called mantra first begin in the earliest period of Indian religion, even if the mantras of the early Vedic texts are not recognizable as prototypes for those found in most Buddhist environments. We first see Buddhists concerned with mantras in their employment for protection, divination, aggression and so on, with worship or contemplation seemingly a second-order phenomenon. However, the form of mantras expressed was drawn from a variety of environments, not from a single source. For Buddhists first encountering such mantras, the problem most definitely became their relationship to the expectations of the Buddhist monastic world, not their soteriological application.