Anciently, the bowman who went forth to battle was ill prepared unless he carried two or more bowstrings.
Otherwise he would be utterly useless if the one on his bow were to snap.
Thus, probably long before Cardinal Wolsey recorded it in 1524, the expression “to have two strings to one’s bow” had acquired the figurative meaning still in use, to have two (or more) resources, or to be prepared with alternate plans for carrying out one’s intent.
