Modest doubt is called
The beacon of the wise.
Shak.
Beacon fire, a signal fire.
Bea"con, v. t. [imp. & p. p. Beaconed (-k'nd); p. pr. & vb. n. Beaconing.] 1. To give light to, as a beacon; to light up; to illumine.
That beacons the darkness of heaven.
Campbell.