John Cassian

About this text you should first take care to observe that Isaiah does not say that "the spirit of fear shall rest upon him" but "shall fill him." The power of it is so abundant that if once it possesses a person in its strength, it possesses his mind to the exclusion of all else. Linked with the charity that never fails, it fills and permanently possesses the soul whom it has seized, and it cannot be lessened by the temptations of any this-worldly happiness.