Soma is the one Vedic offering that is also a god. The substance is a juice pressed from the stalks of a plant, strained and mixed and then poured into the fire and drunk by the officiating priests. The god Soma is that same juice addressed in the second person, praised while it is still running through the filter. The two are not a metaphor for one another; the hymns move between them without marking a change of subject.
Mandala 9 of the Rigveda holds one hundred and fourteen hymns to Soma Pavamana, Soma being purified, and almost all of them describe a single moment, the passage of the liquid through the woollen strainer into the vessels below. The poets reach for every image they have for it: a king riding to his throne, a bull bellowing, a horse let out to run, rivers going down to the sea. No other Vedic substance is given a book of the collection to itself.
The drink belongs above all to Indra. He is said to drink it before he kills Vritra and releases the held waters, so the sacrifice is not a commemoration of that act but the supply line for it, and the priests understood themselves to be strengthening a god who had work to do. Human drinkers speak in the first person too. One much quoted passage has the speaker announce that he has drunk the soma, become immortal, reached the light and found the gods. Whether that is a report of intoxication, an expression of ritual exaltation or a formal claim the rite entitles him to make is argued, and the hymn does not settle it.
The pressing sat at the centre of a large public ceremony, and the later Srauta manuals classify whole rites by how many pressing days they run. The Agnistoma, the model one day soma sacrifice, is still performed.