Obstruction of any sense is an evil for the animal nature; so is the obstruction of any of its impulses. There are other kinds of obstruction which are evil for the nature of plants. For the rational nature in like manner, therefore, obstruction of the understanding is evil. Apply all this to yourself. Do pain and pleasure affect you? Let the senses look to it. Does anything hinder your designs? If you have designed without the proper reservations, that in itself is an evil for you as a reasoning being. If you designed under the general reservation, you are neither hurt nor hindered. No man can hinder the proper work of the mind. Nor fire, nor sword, nor tyrant, nor calumny can reach it, nor any other thing, when it is become even as a sphere, complete and perfect within itself.