RARE 19th-century monograph on logic following the principles of the eminent French philosopher and epistemologist Etienne Bonnot de Condillac (1714-1780) and the influential French philosopher and grammarian César Chesneau, sieur Dumarsais or Du Marsais (1676-1756), prominent figures in what became known as the Enlightenment, both involved with the circle of Denis Diderot. Contains 9 fold-out plates. 205x135mm. 864 pages. Marbled board Hardcover with brown leather gilt spine. Text block edges dyed yellow. Cover rubbed, scratched and age-stained/yellowing. Cover corners and edges bumped and worn. Spine rubbed, stained and slightly wrinkled. Spine edges slightly bumped. Spine edges and hinges slightly peeling. Pencil inscriptions and stamp on rear endpaper. Inner cover and few page (including extreme pages) age-stained. Pen inscription and two small stamps on pre-title whitepage. Plates water-stained and age-stained. Small stains on edges of last page and plates. Some pages slightly age-stained. Pages yellowing and wavy. [SUMMARY]: This extremely rare introductory book on logic, written in the spirit of French Enlightenment, is overall in good condition.