Internationalism No. 85, March 2026 Special Issue, Page I From the series Principles of Marxism In his Anti-Dühring , Engels dwells on the art of working with concepts , explaining that concepts are the results in which experiences are summarised . This art does not arise from innate gifts, intuition, or common sense, but rather depends on a general vision and a method of investigating reality, which Engels describes as real thought, [which] similarly has a long empirical history, not more and not less than empirical natural science . Commenting on this passage, Arrigo Cervetto wrote in February 1990: The thesis can be summarised in the formula of the necessity of theory. The results of experience are summarised in concepts, but without the art of working with concepts , of connecting them, selecting them, and comparing them, there is no theory . The Grundrisse notebooks represent Marx’s broad and system...