375. The correspondence of the will and understanding with the heart and lungs cannot be abstractly proved, that is, by mere reasonings, but it may be proved by effects. It is much the same as it is with the causes of things which can be seen rationally, yet not clearly except by means of effects; for causes are in effects, and by means of effects make themselves visible; and until causes are thus made visible, the mind is not assured respecting them. In what follows, the effects of this correspondence will be described. But lest any one should fall into ideas of this correspondence imbibed from hypotheses about the soul, let him first read over carefully the propositions in the preceding chapter, as follows: Love and wisdom, and the will and understanding therefrom, make the very life of man (n. 363, 365). The life of man is in first principles in the brains, and in derivatives in the body (n. 365). Such as life is in first principles, such it is in the whole and in every part (n. 366). By means of these first principles life is in the whole from every part, and in every part from the whole (n. 367). Such as the love is, such is the wisdom, consequently such is the man (n. 368).