 Although he was only loosely related with any academic environment at that time, Fleck conducted medical research, the results of which he published in about 40 papers, mostly in Polish and in German. In 1927 he published in Polish his first work in the philosophy of medicine: “Some Specific Features of the Medical Way of Thinking”. Two years later he published in German a paper “On the Crisis of ‘Reality’”(1929) inspired mostly by the quantum revolution in physics. Both articles are of a provisional character, but the first one already includes the terms “thought style” and “incommensurability”.