Coulter

Coulter (also coulter or colter) is an agricultural implement that in modern usage refers to the vertical blade on a plow that cuts the soil ahead of the plowshare. In 1 Samuel 13:20–21, the term appears in the context of Philistine control of ironworking: Israelites had to go down to the Philistines to sharpen their plowshares, mattocks, axes, and coulters — a technological dependence that left Israel militarily disadvantaged, since the Philistines would not allow iron tools that could be converted into weapons to be sharpened by Israelites.

The same agricultural tool appears symbolically in the famous peace passages of Isaiah 2:4 and Micah 4:3, where nations will beat their swords into plowshares and their spears into pruning hooks — and in the inverted call to war in Joel 3:10, where the nations are summoned to beat plowshares into swords. The coulter and plowshare thus anchor both the agricultural economy of the ancient world and the prophetic vision of peace as the transformation of instruments of war into instruments of cultivation.