Sage comes directly from the Latin sapere, to know, shared by both the English word for wisdom and the herb long associated with clear-headed judgment. The name states its meaning plainly -- discernment named outright rather than implied through symbol or story.
The comets should be used when they appear and in what they rule; just as fixed stars, they have to be used according to each one's nature. - Picatrix (Andalusia, ~1000.AD)