  Schlick expended considerable effort discussing the differences between intuitive acquaintance and conceptual knowledge, insisting that, even though intuitive images are real, acquaintance with them does not constitute knowledge. This thesis directly confronts the idea, held by a number of philosophers, that acquaintance with intuitive contents is, indeed, a species of knowledge which is more direct and immediate than conceptual knowledge. By comparison, scientific knowledge is regarded as a poor substitute, lacking the intimacy of intuitive acquaintance. Two champions of this belief are  Henri Bergson, who thought that direct access to intuitive contents could (somehow) ‘unite’ the knower with the object known, and  Edmund Husserl, who proposed that a genuinely philosophical intuition could become the basis of a kind of scientific cognition in which the subject is in direct contact with its object, without any symbolism or mathematics, any inferences or proofs (Bergson 1955; Husserl 1965).  Bergson called this intimate perception of objects ‘intuition’ and Husserl called it ‘wesenschau’. But the reason why intuition can never constitute knowledge is, of course, quite obvious to Schlick. On his view, knowledge requires two terms: that which is known and that, as which, it is known. But intuition, considered as an act of consciousness, involves only that which is intuited.  In short, the attempt to identify intuition as a form of knowledge is simply a conflation of knowledge with acquaintance, of unelaborated, direct perception or sensation with conceptual knowledge, of kennen with erkennen (Schlick 2009, Sec. 12).