Spice agony

The spice agony is an ordeal in which a Bene Gesserit acolyte ingests a poisonous narcotic and, by internally converting it into a harmless substance, gains access to Other Memory—the combined ego and memories of all her female ancestors. The ritual originated with the discovery of the poison drug on Rossak, though by the time of Lady Jessica the Rossak drug had been replaced by melange. On Arrakis, Fremen Reverend Mothers use the Water of Life, the exhalation of a drowning little maker, and after the ordeal the changed poison is provided for the sietch orgy.

An acolyte who cannot effect the change dies. Only women have survived the agony, but the Bene Gesserit seek through selective breeding a male Kwisatz Haderach who can change an illuminating poison. Until Paul Atreides, all men who attempted the agony died. Jessica endured the agony while pregnant with Alia, causing Alia to be born a full Reverend Mother with complete Other Memory; such children are called Abominations and are susceptible to ancestral possession.