the.com/balance of power

means a political arrangement in which no single nation or group grows strong enough to dominate the rest, because rivals counterbalance its strength.

from The phrase took root in European diplomatic language, especially around the 1700s, picturing international relations as a literal scale — weights of military and economic strength piled on either side, with peace holding only as long as neither pan dropped too far. It borrows directly from the balance (the weighing instrument), itself from Latin 'bilanx' — 'having two scales' (bi- 'two' + lanx 'dish/plate'). Statesmen of the era used it to justify alliances built purely to keep any one power from tipping the whole continent over.