From Lenin's viewpoint the evidence of our senses could not provide a convincing argument to demonstrate the existence of material objects and Lenin was determined to show that the existence of material objects is a demonstrable truth, open to no doubt whatsoever. It was not this evidence alone but sense experience combined with the causal theory of perception, which was to supply the missing link between mental images and the external world. For Lenin the causal theory was hardly distinct or in need of differentiation from the vague and complex body of direct and inferred knowledge, indiscriminately referred to as "empirical knowledge'. What the causal theory seems to imply was merged in Lenin's thinking with the data of sense experience into an unanalysed whole that endowed the former with its supposed demonstrative power. The "evidence of the senses', of which Lenin made use, is something more than what this expression usually conveys.