Rapithwin's most distinctive doctrine is its seasonal disappearance. In the tradition's reckoning the demon of frost invades the world in winter, and the spirit of noon, rather than yield the field, withdraws beneath the earth, where through the cold months it keeps the underground waters and the roots of plants warm, the reason, the texts explain, that springs do not freeze and vegetation survives to return.
While Rapithwin is below, the noon hours are annexed to the morning watch: the prayer said at midday in winter is a second Havan, and the Rapithwin Gah prayer falls silent. With the spring equinox and the new year, Nowruz, the warmth returns above ground, and the tradition marks the homecoming liturgically: in the first days of the new year the priesthood celebrates ceremonies of welcome for Rapithwin, after which the noon watch resumes its own prayer for the summer half of the year.
Scholars, Mary Boyce foremost, have read the observance as a precious survival of the religion's deep agricultural and seasonal past, a myth that answers a farmer's question, why do the springs still run in January, with an image of faithful warmth holding out below the frost line. It also gives the five-watch system a living pulse: the Zoroastrian day is not the same shape in January as in July, and the returning of Rapithwin each spring makes the year's renewal audible in the simple fact of which prayer is said at noon.