 He died in 1659 at the age of 34.Apáczai wrote his encyclopedia while he was in Utrecht, and it was in Utrecht that it was published, in 1655 (with the year of 1653 printed on the frontispiece), after he had returned to Transylvania.The first part of the encyclopedia consisted of a translation of the philosophy of Descartes, and the second and third covered logic following the earlier treatments of Petrus Ramus and his student Amesius.