372. (1) All things of the mind have relation to the will and understanding, and all things of the body to the heart and lungs. By the mind nothing else is meant than the will and understanding, which in their complex are all things that affect man and all that he thinks, thus all things of man's affection and thought. The things that affect man are of his will, and the things that he thinks are of his understanding. That all things of man's thought are of his understanding is known, since he thinks from the understanding; but it is not so well known that all things of man's affection are of his will, this is not so well known because when man is thinking he pays no attention to the affection, but only to what he is thinking; just as when he hears a person speaking, he pays no attention to the tone of the voice but only to the language. Yet affection is related to thought as the tone of the voice is to the language; consequently the affection of the one speaking is known by the tone, and his thought by the language. Affection is of the will, because all affection is of love, and the will is the receptacle of love, as was shown above. He that is not aware that affection is of the will confounds affection with understanding, for he declares it to be one with thought, yet they are not one but act as one. That they are confounded is evident from the common expression, I think I will do this, meaning, I will to do it. But that they are two is also evident from a common expression, I wish to think about this matter; and when one thinks about it, the affection of the will is present in the thought of the understanding, like the tone in speech, as was said before. That all parts of the body have relation to the heart and lungs is known, but that there is a correspondence of the heart and lungs with the will and understanding is not known. This subject will therefore be treated in what follows.