Why did Dmitri Mendeleev write The Principles of Chemistry?

Dmitri Mendeleev wrote The Principles of Chemistry (1868–71) primarily because he was unable to find an existing inorganic chemistry textbook that met his needs for teaching the subject.1

Having previously authored a successful organic chemistry textbook in 1861, which earned him the Demidov Prize, Mendeleev set out to create a new, comprehensive text. During the process of composing the book, he sought to organize the vast existing knowledge regarding the physical and chemical properties of elements and their compounds. It was through this systematic effort to structure the material for his textbook that he discovered the periodic law, observing that the order of atomic weights could be used to arrange both individual elements and their respective groups.1