Menschliches, Allzumenschliches

Chemistry of concepts and sensations.-At almost every point, philosophical problems are once again assuming the same form for their questions as they did two thousand years ago: how can something arise from its opposite, for example something rational from something irrational, something sentient from something dead, logic from illogic, disinterested contemplation from willful desire, living for others from egoism, truth from error?