That is the title of a new book by Anthony Gottlieb on the life and ideas of the great but perplexing 20th-century philosopher Ludwig Wittgenstein. (I found this 2025 book on the shelves of Shakespeare and Company, an English-language bookshop in Paris.) Among many other things, I have learned that the would-be philosopher had patented an idea for a new type of aircraft propeller in 1911 (see here, for example), when he just 21 years old! (p. 53) I will report back soon.