A wreck on shore is a beacon at sea.
— Proverbs

Modest doubt is called the beacon of the wise.
William Shakespeare beacon quote

There should always be in sight the draw - a kind of a beacon that draws you on through the labyrinth.
— Stewart Brand

To act and act wisely when the time for action comes, to wait and wait patiently when it is time for repose, put man in accord with the rising and falling tides (of affairs), so that with nature and law at his back, and truth and beneficence as his beacon light, he may accomplish wonders. Ignorance of this law results in periods of unreasoning enthusiasm on the one hand, and depression on the other. Man thus becomes the victim of the tides when he should be their Master.
— Helen P. Blavatsky

He who thinks and thinks for himself, will always have a claim to thanks; it is no matter whether it be right or wrong, so as it be explicit. If it is right, it will serve as a guide to direct; if wrong, as a beacon to warn.
— beacon quotation by Jeremy Bentham