  Weyl was a mathematician and a philosopher. He liked to deal with  concepts and the connection between them. His book was very famous,  and was recognized as profound. Almost every theoretical physicist  born before 1935 has a copy of it on his bookshelves. But very few  read it: Most are not accustomed to Weyl’s concentration on the  structural aspects of physics and feel uncomfortable with his  emphasis on concepts. The book was just too abstract for most  physicists.