Successful feuds with the bishops of Strassburg and Basel further augmented his wealth and his reputation; rights over various tracts of land were purchased from abbots and others; and he was also the possessor of large estates in the regions now known as Switzerland and Alsace.
In some birds, such as the herons, certain down-feathers or plumulae break off into a fine dust as fast as they are formed and form tracts defined in size and situation and known as "powder-down patches."
Large tracts of mountain are clothed with fragrant scrub composed of these and other plants.'
The strictures of a critic in the Monthly Review of July 1763 drew from him a pamphlet called Man in Quest of Himself, by Cuthbert Comment (reprinted in Parr's Metaphysical Tracts, 1837), "a defence of the individuality of the human mind or self."
The World was consigned to his desk; and although doctrines in all essential respects the same constitute the physical portion of his Principia, it was not till after the death of Descartes that fragments of the work, including Le Monde, or a treatise on light, and the physiological tracts L'Momme and La Formation du foetus, were given to the world by his admirer Claude Clerselier (1614-1684) in 1664.