No one better than Marcel Bataillon in his Erasmus and Spain to tell us about the book of the great humanist.
He says (and very well) literally copied: "In 1529, the Master Bernardo Pérez... published in Valencia his translation of the Silenos de Alçibiades. This witty essay, part of the Adagios treasure, circulated for a long time. In the Banquete platónico (platonic banquet), Alcibiades compares the rustic coating of the great Socrates, with those boxes that showed outside the face of Sileno; but in which were kept, as the author of Gargantúa says, "las finas drogas, pedrerías y otras cosas preciosas" (fine medicines, precious stones and other precious items).
The image, famous amongst the wise men, served as a starting point for Erasmus. Other philosophers such as Diogenes and Epictetus hid their wisdom under their humble clothing.
Erasmus however, as you can guess, is elevated to the same level as Christ, an image of supreme wisdom, which gets rid of all pomp and is covered by humility; Saint John the Baptist and the Apostles are also Silenos in their way.
The stories of the Old Testament, the parables of the New Testament, force us to see through the appearances and be surprised by the divine secret.
However, inversely, one must know when to spot fake grandeur, discover a tyrant masked by royalty, the warrior or the business man under the Episcopal vestments, the sensual man and full of passions under the friars' vests, the bandits who used the name of a 'just war', the preparation for war under the beautiful name of peace.
Finally, the true Church must be found (who knows, the community of the faithful), behind the ecclesiastical hierarchy.
The translator softened (and censured) Erasmus' text: "Atenuación de las críticas contra la Iglesia jerárquica y los frailes, exaltación del sentimiento de la gracia que renueva los corazones: tales son, decididamente, los dos aspectos complementarios de la metamorfosis que sufre el pensamiento de Erasmo en tierra española". Bataillon dixit. (Minimising the criticisms against the church's hierarchy, friars, exaltation of Grace which renews the hearts: those are, decidedly, two side aspects of metamorphosis, which Erasmus' thinking takes in Spanish land. Bataillon dixit).