In the paper I present my path towards the sandwich theory of knowledge, which I have been travelling for about three decades. It started from a modest remark by R. Wójcicki who drew my attention to the concept of presupposition. This concept played an important role in my analyses of the growth of science, which I have been occupied with for much of my career. At that time I was also impressed by A. Wiśniewski’s erotetic logic. Later, I took more interest in epistemology, first for teaching, subsequently also for study. I point also to other sources of inspiration: Ajdukiewicz, Hintikka, Popper, Putnam, and Wittgenstein.