Under the influence of Leibnitz in oposition to Kant, especially against his philosophy of mathematics, Bolzano analyses several topics discussed in analytic philosophy of today. His starting point is a distinction of concepts and intuitions, being two basic kinds of ideas-in-themselves, based on the postulates of nonemptiness, singularity and simplicity. This dichotomy is utilized in the analysis of conceptual and empirical sentences (judgements), the analytic/synthetic distinction and the a priori and a posteriori differentiation. His classification of analytic sentences, based on his logic of variation and the degree of validity, in a narrow and broader sense corresponds to the contemporary view of analyticity for logical and linguistic reasons. Inspite of his ontological atomism he anticipates Quine´s holism according to which empirical sciences are theory-laden. He even accepts, at least for historical reasons, his empiricism concerning the role of observation sentences in theoretical sciences. According to Bolzano, no sharp demarcation between conceptual and empirical sciences can be drawn.