Antonio Rosmini was an eager reader of philosophical classics and a deep connoisseur of tradition. His work can be intended as a transparent personal contribution to the thoughts of authorities. The idea of being is a delicate issue and seems to be strictly related to that lumen, which he knew through medieval philosophers' works. The author reviews several contemporary studies in order to appreciate Rosmini's critics’ condition regarding the re-lationship between ideal being and scholastic theory of illumination.