Since research on the homa is important for both ritual studies and the study of Asian religions, it is a nexus of interaction for these two fields of study. It is important for ritual studies because this one ritual, despite particular sectarian inflections, has a history of more than two millennia, and the Indo-Iranian and Vedic rituals that form an important part of the source material for its development, extends that history to as much as four millennia. Over the course of its history, the homa has spread out from the Indian subcontinent into several different religious cultures, and in addition to South Asia, it is also found in Central Asia, East Asia, Southeast Asia, as well as now in Europe and the Americas. It is, therefore, one of very few instances of a ritual that can be studied over the longue durée, having undergone repeated ritual change and cultural adaptation while at the same time retaining an extensive and detailed textual record, and a clearly identifiable continuity of ritual practice.2
The homa employs a fire into which offerings are made. Although sometimes spoken of—rather loosely—as a sacrificial ritual, since the offerings are destroyed in the fire, it is more appropriate to consider it a votive ritual. That is, the offerings are being conveyed to the deities in expectation of a quid pro quo. One of the unifying factors for homas in almost all traditions is that the fire is identified as Agni, the Vedic fire god. Agni is central to Vedic fire rituals and those that derive from them because by consuming the offerings, Agni makes them pure and only then conveys them to the gods. Additional sets of offerings to other deities may be added into a ritual performance of the homa, but Agni is almost invariably the first deity evoked.3
Other similarities uniting the homa as performed across the range of traditions in which it is practiced include the kinds of offerings made, the altars upon which the ritual is performed, and the implements employed in the performance of the ritual. The offerings frequently include both material and symbolic offerings, such as clarified butter or oil, grains and beans of various kinds, lights, incense, water for washing the deities’ feet, music, and so on—the specific combination of offerings and the specific kinds of offerings varying according to ritual culture. Such variations at times further reflect material culture as well, such as in the kinds of substitutions made for the substances offered.4 There are also consistent similarities in the shapes of the altar hearths employed for the performance of homas having different purposes. While several traditions homologize the altar with a mandala, for the performance of a homa the altar is the hearth that contains the fire, and such hearths usually take one of a limited number of shapes. The shapes of hearths include circles, demilunes, stars, and so on, and specific shapes are employed for different ritual ends. Likewise, the implements employed in the performance of a homa are similar across various ritual cultures. A widely shared instance of the implements employed are the ladle and a spoon used to make offerings. Although the sizes and shapes of these implements also vary across ritual cultures, the use of those two paired implements is also consistent and is one of the ritual details significant for demonstrating continuity from Vedic through to tantric ritual practice.
By comparison, implements are also important for the study of the history of the Zoroastrian fire ritual, the yasna. Michael Stausberg has noted that there are limitations on what one can conclude regarding the antiquity of the yasna on the basis of archaeological evidence, specifically mortars and pestles found in both performance of the yasna and in ancient sites such as Persepolis. Although the existence of mortars and pestles dating from the fifth century B.C.E. indicate the possibility that the yasna was performed that early, “the fact that similar or even identical implements have been used in a ritual context does not in itself constitute a valid proof for the hypothesis that it was ‘the Yasna’ that has been performed with the help of these vessels.”5 In the case of the spoon and ladle used in the homa, however, the implements are not isolated from other ritual elements. In other words, the implements form part of a network of interrelated ritual elements, including other ritual implements, the shapes of altars, and the kinds of offerings made.
Other specific ritual elements found in performances of the homa also point to the historical continuity with Vedic ritual culture. One telling instance is the ritual construction and destruction of the altar as found for example in the Japanese esoteric Buddhist tradition of Shingon. A defining characteristic of Vedic ritual culture is that ritual spaces are temporary constructions, usually interpreted as a consequence of the nomadic character of Vedic society. This is a clear difference from the fixed ritual sites of temples in Brahmanic and Hindu religious cultures. As temporary constructions, Vedic ritual action includes the construction and destruction of the ritual enclosures.6
Today in the Shingon tradition of Japanese esoteric Buddhism, the same actions—ritualized as symbolic ones—remain part of homa performance. As the final of the four rituals in the training sequence (shidō kegyō 四度加行) of a Shingon priest, the sequence of homa performances starts with the ritual construction of the altar and ends after several days of practice with its ritual destruction as well—it is dissolved into the five elements of the cosmos.7 Thus, although for probably centuries Shingon ritual practice has been done inside temple buildings at permanent altars, we find an almost vestigial remnant of the outdoor, temporary ritual enclosures of Vedic ritual practice. Other kinds of continuities and adaptations took place across the history of the homa. Adaptations are found in the religious cultures of China and Japan where interactions between the practices of the homa and other ritual practices were created. For example, Christine Mollier has discussed the development in China of a homa devoted to the seven stars of the Great Dipper.8 Similarly, in medieval Japan a Shintō version of the homa and other rituals based on tantric Buddhist prototypes were also developed.
As indicated by this brief description, the homa has been transmitted across the boundaries between several religious cultures, as well as having retained elements that point to a continuity of history extending over millennia. With roots in the rituals of Indo-Iranian and Vedic religious practices, and branches extending across the entire tantric world, it has been adapted to a variety of different purposes and cultural settings. In addition, it is a very well documented ritual, including canonic descriptions, manuals for performance, polemical discussions, and the like. This makes it one of the best possible rituals for studying ritual change over a long period of time and across religious cultures.9 Before moving on to the issues involved in the study of ritual change per se, it will be useful to consider the category of ritual and how it has been distinguished from other related phenomena, such as ceremonial and festival. Examining how categories are formed reveals either explicit or implicit theoretical commitments.