Kava is prepared by pounding, grating or formerly chewing the root of Piper methysticum and steeping it in water to make a cloudy, peppery, earth-tasting drink. It is a sedative rather than a visionary plant: it relaxes the muscles, loosens speech, numbs the mouth and produces a sociable calm without confusion. That effect is exactly suited to the work its ceremonies do.
Across Fiji, Tonga, Samoa, Vanuatu, Pohnpei and beyond, kava is the drink of formal occasion, and the ceremony is a statement of order. The cup passes in a sequence that expresses rank, and who is served first, who prepares it, who calls the toast and where each person sits are all determined and all meaningful. A chiefly installation, the reception of a visitor, the opening of a council, the settling of a dispute and the sealing of an agreement are all done over kava. In Tonga the formal kava circle is an institution of state; in Fiji the presentation of a root, sevusevu, is how a visitor asks permission to be somewhere.
The religious dimension is not separable from the political one, which is the point. The ancestors and the spirits are present at these occasions, the first cup may be poured out for them, and the authority the ceremony confirms is understood to come from them. Kava is the medium in which a community says what it is.