An altar may be defined either as a place where the gods sit or as a place at which offerings are made. (The use of "altar" in many Neo-Pagan groups today to describe a table on which tools are put until needed, most likely derives from Christian usage by way of ceremonial magic.) In a particular ritual, these two definitions may be represented by two different structures, the same structure may serve both purposes, or only one kind may be present.
That the Proto-Indo-Europeans used altars of some kind may be assumed on linguistic grounds; they had deities (*deiwós) to whom they made offerings (*gheu-) (York, 1993, 241-2). They must have had altars at which to make their offerings. Their descendants, the Indo-European peoples, made their altars almost uniformly of stone, a material which is, however, unsuited to the assumed nomadic lifestyle of Proto-Indo-Europeans. A less permanent building material must have been used. It is my contention that by looking at the religious practices of Indo-European peoples, this material may be identified.
At one end of the Indo-European world we find the Scots. There are a records from the eighteenth century of building May Day fires on a pile of turf (Frazerís note on Ovidís Fasti, 417).
Preserved in the Christian Anglo-Saxon spells, presented by Grendon (1909), are tidbits of Pagan ritual. The most suggestive of the spells, the Land Remedy Spell (A13), seems to contain a ritual for the creation of sacred space. Prescribed for restoring fertility to land, it involves taking four sods, one from each side of the land. Their undersides are to be sprinkled with holy water while a prayer is said.
First, however, something is done with "oil and honey and barm, and milk of all cattle on the land, and every part of every kind of tree growing on the land, except hard trees, and part of every known herb except burdock alone." Just what is to be done with these is not said, except that they are to be sprinkled with holy water. The articles mentioned, however, seem first to be intended to represent the life of the land in its entirety, with the exception of hard trees and burdock, representative perhaps of the sort of plants that are not desired to be made fertile. They seem as well to be typical sacrificial items, especially the oil, honey, barm, and milk, as well as wood for making a small, hot fire.
The sods are brought to church, where masses are said over them, the green parts toward the altar. The sods are then returned to their original places, and crosses of aspen wood laid in the hole before they are replaced. These sods are certainly stand ins for the land as a whole. However, the sacrificial offerings, the orientation towards the altar in church, and the connection with the crosses clearly identify them also as altars.
The Romans, in Augustan times, had the tradition of placing a sod on their stone altars before sacrifice (Ogilvie, 1969, 47). This was in memory of ancient times, when altars were made from sod. A sod altar is also found in the Aeneid (117ff.). These altars served as places to make offerings.
The Indo-Iranians had grass altars (Skt. barhiṣ, Av. barezish). This grass might be strewn on the ground (Van den Bosch, 1985, 104), or placed on a small structure (Renou, 1971, 99). The same word, vedi, is used in Vedic rituals for the pile of barhiṣ and the structure on which it might be placed. The barhiṣ is anointed with ghee and the gods are invited to seat themselves on it, thus serving as both offering place and place of the gods. Fires are built separately, and serve as the main offering place.
In Zoroastrianism fire has become too holy to be polluted by offerings, except of purest sandalwood. It is the resting place of Ahura Mazda. The function of place of offerings belongs to the grass.
From these four groups, Celtic, Germanic, Italic, and Indo-Iranian, we can suggest the material used for altars in Proto-Indo-European days. The western two examples both use sod, and the Indo-Iranian use grass. The grass is most likely a result of the separation of the fire of offering from the seat of the gods in Vedic ritual. Grass is not suitable for a fire base, of course, but it is very suitable for a seat. Zoroastrianism has reversed the offering and seat attributions as a result of the worship accorded to the fire.
It is reasonable, then, to suggest that the Proto-Indo-Europeans made their altars of sod. Fires were lit on these altars, which were then considered to be both the place where the gods came to be with their people and the place where offerings were to be made to the gods.
Boyce, Mary (ed. and tr.). Textual Sources for the Study of Zoroastrianism. Manchester, UK: Manchester University Press, 1964.
Grendon, Felix. The Anglo-Saxon Charms. Journal of American Folklore 22 (April-June, 1909), 105-237.
Ogilvie, R. M. The Romans and their Gods in the Age of Augustus. New York: W. W. Norton and Co., 1969.
Ovid. Fasti. Ed. and tr. James George Frazer. London: MacMillan and Co., 1929.
Renou, Louis. Vedic India. Tr. Phillip Spratt. Varanasi, India: Indological Book House, 1971.
Van den Bosch, Lourens. The Apri Hymns of the RgVeda and their Interpretation. Indo-Iranian Journal 28<.i>:3 (1985), 95-122, 28:3 (1985), 169-189.
Vergil. The Aeneid. tr. Allen Mandelbaum. New York: Bantam Books, 1961.
York, Michael. Toward a Proto-Indo-European Vocabulary of the Sacred. Word 44:2 (Aug., 1993), 235-54.