This study, published posthumously, deals with the question of ideas in God’s mind in the treatise De ideis of John Wyclif, who had a significant influence on Jan Hus and other masters of the Bohemian nation at the Prague University. In the first part the text focuses on the question of the publication of an edition of the hitherto unpublished Wyclif’s treatise; in the second part, on the basis of this text, is presented Wyclif’s conception of ideas. The article displays both Wyclif’s arguments and the authorities which Wyclif drew upon. Finally, in the last part, the article looks at the criticism of Wyclif’s teaching about ideas on the part of John Cunningham, Thomas of Walden and Jean Gerson, who, on this basis, imputed to Wyclif a heretical pantheist doctrine.