The Half-Saved Soul

Well versed himself in the dangers of the world, the confessor listened with feeling, and answered with wise words.

He showed Ignatius Loyola how Satan slips into the very act of conversion, and prompts the half-saved soul to spiritual pride; he pointed out the true life for the penitent to pursue, and the dangers he would need especially to guard against; he sketched for him the varying features of the Evil One, 

so that he might know them even when they came before him in the guise of an angel's countenance.

Link (here) to The Writing of James Handasyd Perkins