How can we perceive the truth? Was it naive for the ancients to think it was "the Muses" or some such who guaranteed the truth was the truth? Was Descartes way off base to think the Christian God guaranteed what we thought of as certain as indeed...certainly true? Today people still endorse ideas about "not possibly being mistaken" - but what is their basis for thinking this if not "the divine guarantor"? Here Popper continues his masterclass in the history of epistemology explaining how we have arrived at the place we are at today. He explains how knowledge creation is a process of sifting the true from the false - but how does that work? In a wonderful example Popper does this before our eyes with epistemology itself - sifting the true and false, better and worse, good and bad ideas from the ancients and classics into his own epistemology: a refined optimism of how knowledge is possible and we can all learn whatever it is anyone else can learn. It's a matter of conjecturing and correcting errors. There is no room left for someone feeling pessimistic that they cannot possibly learn a thing.