Cordage—rope—was one of the first and most necessary tools. Its use is among the first lessons of “wilderness survival” courses, as cord made from found fibers may be used for fishing lines or snares; it can lash shelter structures or be used to string a bow.
Cordage functions only under tension: Unless you count the pounding a thump-mat gets around a flopping block, it has no compression role. But this single attribute has made cordage inseparable from the progress of civilization. Rope is made from simple twisted fibers, yet it’s not so simple. There’s a subtle virtue in its twist, allowing it to flex to accommodate loading so that each fiber takes generally the same strain. A cord made of straight fibers clumped together would be pitifully weak: The weakest fiber would break and increase the load on other fibers; more breakage would occur, and failure would ensue.
The simple twisting of either natural or synthetic fibers can create enormous tensile strength. Left-twisted gatherings of fiber are right-twisted into cords or yarns. These can be left-twisted into composite strands. The strands can then be right-twisted into a rope. Right twists are “locked” by left twists. This inter-supporting structure is called laid rope. It flexes to balance strains.