The Evolution of Useful Things A Book by Henry Petroski Here, then, is the central idea: the form of made things is always subject to change in response to their real or perceived shortcomings, their failures to function properly. This principle governs all invention, innovation, ingenuity. Spike and sponShaped and reshapedForm follows failureTheir wrongness is somehow more immediateA small corner of the world of things+23 More The evolution of devices formfunctioninventionprogressfailure