The seminar is dedicated to the influence of Neoplatonism on the philosophy of mathematics of A.F. Losev. The occasion for the seminar is the new edition of the book "The Dialectic of Number in Plotinus," completing a large publishing project on the works of Losev from 1927 to 1930. This significant reissue signifies the return of fundamental texts to the current intellectual discourse. The report by V.P. Troitsky will touch upon the key ideas of the book, including the interpretation of one of the most complex treatises of late antiquity - Plotinus' work "On Numbers," translated from Ancient Greek by Losev himself. The focus will be on the dialectic of number - a concept in which number is viewed not as an abstract mathematical expression, but as a category of cognition and a means of penetrating the structure of the world. The report also addresses the influence of ancient ideas on Losev's philosophy of mathematics, which later took shape in his work "Dialectical Foundations of Mathematics." The event is aimed at students, graduate students, researchers, and anyone interested in the history of philosophy, Neoplatonism, dialectics, and the philosophy of number. For other events in Moscow, check KUDAGO.