Prophet's Codex

The Prophet's Codex was a codex written by Ezio Auditore da Firenze, Mentor of the Italian Assassins, detailing some of the most important events in his life. One such event was his meeting with Minerva in the Vatican Vault, whose speech he wrote down in great detail.

By the 21st century, the Prophet's Codex was located in the hidden library of beneath the  in Moscow. Daniel Cross, a Templar agent, infiltrated the library posing as the guarding Assassin's replacement. He opened the codex and read Minerva's speech to Warren Vidic before taking it with him and killing the Assassin guard.

Source

 * Assassin's Creed: The Chain