The subject of this book is an epistemological consideration concerning the nature of knowledge. But other than the most essays on the subject of knowledge, here I am going to deal with a largely overlooked account to try to find an answer to the question of knowledge. This is the mental state account of knowledge. Or to put it into the main question: is knowledge a mental state? Now, the question is: Why is the epistemic thinking of Cook Wilson, Prichard and Austin afflicted with such ignorance in contemporary epistemic discussions? The answer is: an unreflected Platonian heritage during 2000 years of epistemic thinking - a notion which is similar to a point Hetherington has called "epistemic absolutism". So my main conclusion here is: the JTB thesis (knowledge is some aspect of justified true belief) is insufficient in order to give an account of the nature of knowledge. A consequence from this is: all the epistemic theories which are dealing with the JTB thesis are based on deficient assumptions. Hence their results - notably the well-known externalism/internalism debate - are insufficient, too. So, there is a need for a new theory of knowledge based on the MS thesis.