Se intenta trabajar como podría ser el tratado “Psychologiae de ratione animae humanae” escrito por Marko Marulo entre 15101524. El tratado se considera perdido en el presente. Se cree que es el primer tratado de Psicología escrito. Marko Marulo ingresó en la orden franciscana en el momento que ha escrito su tratado. Para hablar del contenido del tratado, se supone necesario hablar de los Libros Deuterocanonicos de la Biblia, en segundo lugar hablar sobre la orden Franciscana y en tercer lugar hablar sobre la obra completa de Marulo. Palabras clave Deuterocanonicos Voluntad deseo Franciscana ABSTRACT ATTEMPTS OF RECONSTRUCTION OF THE LOST MARCOS MARULO’S TREATY OF PSYCHOLOGY - OF FRANCISCAN ORDER- OF CENTURY XVI it is tried to elaborate in the present work as could be the content of the treaty “Psychologiae of ratione animae humanae” written by Marko Marulo between 1510-1524. The treaty written by Marulo is considered lost in the present. On the other hand, one thinks that the treaty of this author is first who treats on Psychology in itself. Sources indicate that Marko Marulo entered in the franciscana order at the end of his life, at the moment that has written its treaty of Psychology. To speak of the content of the lost book, assumes necessary to speak of the Deuterocanonicos Books of the Bible, secondly to speak on the Franciscana order and thirdly to speak on the complete work of Marulo. will be tried to work because in the Franciscana order the word arises Psychology and in others you do not order. As more important factor considers the franciscano shade of teorizaciones on the will. Key words Deuterocanonics Will wish Franciscan