Dark blue cloth boards with gold lettering on front cover, green lettering on spine. There are a few scratches and bumps to the cover, slight wear around edges and corners. Book plate noted inside front cover. The pages are heavy and yellowing. The text is clean and intact, the binding is tight. Translated by Robert W. Lawson M.Sc. There is an etching of Einstein dated 1920. A boigraphical note on the author is included here. DATE PUBLISHED: 1921 EDITION: 168 PAGES.