The sensibility of the conscience may be perfected, like the aesthetic sense, till it can recognize and at last enjoy "good," up to the very limits of the absolute, and also until it becomes sensitive to the very slightest deviations towards evil. He who feels thus is "saved"; he who feels less must be more vigilant, and do his utmost to preserve and develop that mysterious and precious sensibility which guides us in distinguishing good from evil. It is one of the most important acts of life to examine our own consciences methodically, having as our source of illumination not only a knowledge of moral codes, but of love. It is only through love that this sensibility can be perfected. He whose sense has not been educated cannot judge himself. A doctor, for example, may be perfectly informed as to the symptoms of a disease, and may know exactly how cardiac sounds and the resistance of the pulse are affected in diseases of the heart; but if his ear cannot perceive the sounds, if his hand cannot appreciate the tactile sensations which give the pulse, of what use is his science to him? His power of understanding diseases is derived from his senses; and if this power is lacking, his knowledge in relation to the sick man is vanity. The same holds good of the diagnosis of our own conscience; if we are blind and deaf, innumerable symptoms will pass unobserved, and we shall not know on what to found our judgment. The tedium of futile undertakings will oppress us from the first moment. On the other hand, it is "feeling" which spurs us on towards perfection. There have been persons with an extraordinary power of recognizing good and evil, just as the Greek artists showed extraordinary powers of recognizing the normal forms of the body under the guidance of the aesthetic sense. Saint Teresa tells us that when some worldly person who was not good approached her, she suffered as if she were inhaling a bad smell. She explained that of course she did not smell anything at all, in the material sense; but that she actually suffered, not merely in imagination; her suffering was a real spiritual distress which she could not tolerate.