'Delirium' is Latin for 'going out of the furrow' — a wandering plough as an image of madness.
An acutely disturbed state of mind characterized by restlessness, illusions, and incoherent thought and speech, occurring especially during fever or intoxication; wild excitement or ecstasy.
From Latin 'dēlīrium' (madness, derangement), from 'dēlīrāre' (to be deranged, to rave), literally meaning 'to go out of the furrow' — composed of 'dē-' (away from) and 'līra' (a furrow, a ridge between furrows in plowing). The agricultural metaphor is vivid: a deranged mind is like a plowshare that has left the furrow, wandering erratically off the straight line. The same metaphor survives in English
The Latin metaphor behind 'delirium' — going out of the furrow — reveals how deeply agricultural imagery was embedded in Roman thought. The Romans saw the well-plowed field as a model of order and sanity, and deviation from the straight furrow as a metaphor for mental disorder. This same plowing metaphor survives in English