This book is a study by Russian scholar Nikolai Petrovich Ostroumov (1846-1930) on Arabia, the Quran and Islam. The main text is preceded by Ostroumov's memoirs about the student experience he received in the 1860s and 1870s in the missionary anti-Muslim department of the Kazan Theological Academy, where he studied Tatar and Arabic languages ​ ​ and Islamic culture. At that time, the authorities of the Kazan Territory, whose population consisted of Tatars and other Muslim ethnic groups, allowed the teaching of the Tatar language in schools to baptized Tatars, as well as using it in Orthodox churches.