“Pure sensism leads inevitably to universal doubt; if reality is in the end reducible to sensible appearance, then, since this is in a state of perpetual flux and self-contradiction, no kind of certitude will any longer be possible. [...] Truth is necessary and immutable; but in the sensible order nothing necessary or immutable is to be found; therefore sensible things will never yield us any truth.” RealityTruthImmutabilitySensible Things Author:Étienne Gilson