Beacon

(bē'kn), n. [A-S. beacen, becen, O. S. bokan, Fries. baken, beken, sign, signal, D. baak, Ger. bake.] 1. A signal-fire to notify the approach of an enemy. No flaming beacons cast their blaze afar. Gay.

2. (Naut.) A signal or conspicuous mark erected on an eminence near the shore, or moored in shoal water, as a guide to mariners.
3. A high hill near the shore. [Prov. Eng.]
4. That which gives notice of danger.

Modest doubt is called The beacon of the wise. Shak.