Pierre Chaunu (b. 1923) is a renowned French historian, the author of many major works, who has largely updated the methods of his profession. The book “What I Believe” was published in Paris by the Bernard Grasse publishing house, in a series of the same name, which presents all the colors of the political spectrum, the most prominent names of the French intelligentsia. In this book, which the author considers as his modest contribution to apologetics, issues of religion (Christian - and not only), as well as issues of faith in general, are discussed in the light of the achievements of modern science and, in particular, natural science. The book should find a grateful reader among people of faith - church and non-church people, for whose spiritual quest it will undoubtedly become a significant help. A man of bright social temperament, Pierre Chaunu will certainly win many friends among Russian-speaking readers, especially those who are characterized by an active attitude to life.