Introduction

St. Thomas Aquinas in his Summa Theologiae asks the question, whether a beatified angel can sin. He responds: It belongs to the perfection of its liberty for the free will to be able to choose between opposite things,. But it comes of the defect of liberty for it to choose anything by turning away from the order of the end. And this is to sin. Hence, there is greater liberty of will in the angels who cannot sin than there is in ourselves.