The Commens Dictionary
Quote from ‘A Brief Intellectual Autobiography by Charles Sanders Peirce’
As to phenomenology, [Peirce] is of opinion that there are at least two sets of categories. After devoting two years to the study of one of these, which corresponds with Hegel’s categories, he became discouraged by the difficulty of attaining any satisfactory approach to certainty, and abandoned the subject. On the other hand, he has found another set, corresponding to Hegel’s three stages, more easy to investigate and extremely useful. He calls these the cenopythagorean categories. They are three in number, Firstness, Secondness, and Thirdness.
This quote has been taken from Kenneth Laine Ketner's 1983 reconstruction of Peirce's 'Autobiography'. Ketner identifies the source as "variant pages" of the manuscript.