Forewarned is forearmed

What is the origin of the phrase “To be forewarned is to be forearmed,” or “forewarned is forearmed”?

The English phrase first appeared in the 1500s. Shakespeare used an expression similar to this in his play Henry VI, Part 3:

“Well I will arm me, being thus forewarn’d.”

The English phrase probably derives from the Latin “Praemonitus, praemunitus.” Translated into English it means, “Forewarned is forearmed.” Various scholars report that the proverb can been traced to Treatises of Fistula by J. Arderne (circa 1425). In 1615, it was used by Miguel de Cervantes used it in Don Quixote.

The proverb suggests that prior knowledge of something allows one to be prepared for it.