Pyotr Ilyich Tchaikovsky, the great Russian composer, conductor, and teacher, kept diaries for most of his life. He recorded everything that happened to him and those around him, wrote down intimate thoughts and observations, and made judgments about his contemporaries—along with his own and others’ secrets. He never showed them to anyone and, in the end, burned almost all the notes. The remaining papers (11 notebooks) were collected by his brother Modest, and later published in 1923 by another brother, Hippolytus, together with Nikolay Timofeyevich Zhegin, the first director of the P. I. Tchaikovsky House-Museum. Notes in the "Diaries" belong to Nikolay Zhegin’s hand. In this edition, Pyotr Ilyich Tchaikovsky’s diaries are published alongside the full text of memoirs about him—his close friend and colleague, professor at the Moscow Conservatory. Nikolay Kashkin’s "Memoirs of P. I. Tchaikovsky," written with immense warmth and love soon after the composer’s death, are the first creative biography of Peter Tchaikovsky and contain extremely valuable evidence about his artistic taste and personal traits.