Abstract: Spinoza is considered to be the most consistent representative of rationalism in philosophy, but this doesn’t mean that he always irreproachably followed the rationalistic ideal in his thinking. The article inquires into the relation of basic speculative notions of Spinosa’s philosophy to the empirically interpreted ideal of rationality of thought. With this aim in view empirical meaning of these concepts which Spinosa adopted from traditional speculative philosophy and partially reconsidered in accordance with his philosophical system has been analyzed. In course of this research we have shown, on the one hand, the ambiguity of the empirical meaning of these traditional concepts – and here one can see the essence of the flaw in the logics of Spinosa’s rationalism, the system based on these concepts, but, on the other hand, the idea that in the context of Spinosa’s philosophy these concepts can still be thought of in speculative empirical terms.