In this lecture, Professor Balis discussed the intriguing theoretical notebook of Peter Paul Rubens. This notebook, which is also known as Rubens’s pocket book, was the subject of his lecture at the conference on “Rubens and the Human Body” (University of York, 17–18 September 2010) and is analyzed in depth in Part XXV of the Corpus Rubenianum Ludwig Burchard. You can read more on this subject in Balis’s article in The Rubenianum Quarterly.