There are two direct references to the horse sacrifice in the Rigveda.[141] The animal is “covered with rich trappings” and led thrice round the altar. It is accompanied by a goat, which is killed first to “announce the sacrifice to the gods”. A goat was also slain at a burial to inform the gods that the soul was about to enter Heaven.

In the Story of Nala and in the Ramáyana, the horse sacrifice is performed to secure human offspring. A second Ramáyana horse sacrifice is offered as an atonement after the slaying of the demon Ravana. An elaborate account of this great ceremonial is also given in the Mahábhárata. It was performed after “the great war” on the advice of the sage Vyasa to atone for the slaying of kinsmen. The horse was let loose and an army followed it. Whichever country the animal entered had to be conquered for the owner of the horse, so that only a powerful monarch could fulfil the conditions of the sacrifice. A hundred such sacrifices might enable a king to depose Indra.

It is significant, however, that the animal was released to wander from kingdom to kingdom on the night of the full moon in the spring month of Choitro, and that it returned in the following year at the close of the winter season. When the ground was prepared by being ploughed by the king, the queen followed him, sowing the seeds of every kind of vegetable and curative herb which grew in the kingdom. A countless number of representative animals were sacrificed before the sacred horse was slain, the rain drum and trumpet were sounded, and the king and queen were drenched with holy water.

The flesh of the horse was cooked and eaten, and Indra and the other gods appeared and partook of their portions. Pieces were also flung in the fire, and the fire received also its meed of Soma. When the sacrifice was completed, the king divided the herb offerings among the people; what remained over was burned.

In the Mahábhárata a white horse is sacrificed, but in the Ramáyana a black victim is offered up. White horses were sacrificed to Mars by the Romans; the Greeks sacrificed white horses to the sun by throwing them in the sea; the Spartans offered up their horses, like the Buriats, on a hilltop.

There can be little doubt that the Greek and Roman horse sacrifices were also intended to ensure fertility. A horse was offered up to Diana at the August harvest festival, and we know that that popular goddess gave plentiful crops and was the guardian of flocks and herds and wild animals of the chase; she also presided at birth, and women invoked her aid. Virgins and youths took a prominent part at this harvest festival. The Roman horse sacrifice took place on 15 October. The animal was offered to Mars; the head was conveyed to the king's house[142] and decorated with loaves, and the blood was preserved until April, when it was mixed by virgins with the blood of calves; this mixture was given to shepherds to ensure the increase of flocks which were fumigated. In the Mahábhárata the king and the princes stand for a time in the smoke belching from the altar, to be cleansed of their sins.

The Persians, and other peoples of Aryan speech and custom, sacrificed horses regularly. But the custom was not confined to Indo-Europeans. The Scythians,[143] who were probably Mongols, not only offered horses to the Spirit of Fertility, but also, like the Buriats, to the dead. The Patagonians sacrificed horses to tree spirits. In this connection it may be noted that some European horse sacrifices took place in sacred groves; the Buriats tied their horse to a birch tree, which was carried to the mountain top and fixed to a stake; the Indian sacrificial posts were probably substitutes for trees.

In the Upanishads the sacrifice of the horse is infused, as we have indicated, with mystic symbolism. We read: “The dawn in truth is the head of the sacrificial horse. The sun is the eye; the wind the breath ... the year the body, the heaven is the back ... the constellations the bones; the sky the muscles; the rivers, arteries and veins; the liver and spleen, the mountains; the herbs and trees, the various kinds of hair.” The horse is also identified with the sun: “The sun, as long as he rises is the fore part of the body; the sun, as long as he descends is the hind part of the body, &c.” The horse is also day and night in turn, and its birthplace is the sea; it carries the gods and the Asuras; it is the symbol of Death, “who is voracity”, from whom all things came. “There was not anything here before.” Death first “created this mind, desiring, May I have a soul. He went forth worshipping. From him, when worshipping, the waters were produced.... The froth of the waters which was there became consistent. This became the earth.... He made himself threefold. His eastern quarter is the head ... his western quarter is the tail, &c.”

The work of Creation proceeds, and then “he (Death as the Creator) resolved to devour all that he had created; for he eats all.... He is the eater of the whole universe; this whole universe is his food.”

After a year of purification the Creator slaughtered his horse body. “He gave up the animal to the gods. Therefore they (the gods) slaughter the purified animal, representing in its nature, as Prajápati, all deities. He (the Creator) is the Ashwameda[144] who shines.”