Faust Vrančić wrote philosophical and theological texts. Under the pseudonym he published two works, namely Logica suis ipsius instrumentis formata (Justus Verax Sicenus, Rome, 1608) and Ethica cristiana (Justus Verax Sicenus, Rome, 1610). Vrančić asked logicians to evaluate his work in which he did not follow the former Aristotelian logic. An opinion on Vrančić’s logic was given by a philosopher, physicist and mathematician, archbishop of Split Marko Antun de Dominis. In 1616, a single volume of Logica nova suis ipsius instrumentis formata et recognita was published in Venice, which was partly changed and extended text of Logica from 1608, in addition, the unchanged text of Ethicae christianae was published as an appendix, signed with Vrančić’s real name.