We see, then, that even from the zoological point of view, which is the least interesting and—note this—not decisive, a being in such condition can never achieve a genuine equilibrium; we also see something that differs from the idea of challenge-response in Toynbee and, in my judgement, effectively constitutes human life: namely, that no surroundings or change of surroundings can in itself be described as an obstacle, a difficulty, and a challenge for man, but that the difficulty is always relative to the projects which man creates in his imagination, to what he customarily calls his ideals; in short, relative to what man wants to be. This affords us an idea of challenge-and-response which is much deeper and more decisive than the merely anecdotal, adventitious, and accidental idea which Toynbee proposes. In its light, all of human life appears to us as what it is permanently: a dramatic confrontation and struggle of man with the world and not a mere occasional maladjustment which is produced at certain moments.
~ José Ortega Y Gasset