405. That these three things from the love which belongs to the will follow in sequence in the understanding can indeed be comprehended by a rational man, but not yet seen clearly, and so cannot be confirmed to the extent of faith. Now since love which belongs to the will acts as one with the heart by correspondence, and wisdom which belongs to the understanding acts as one with the lungs, as shown above, what has just been said (n. 404) concerning affection for truth, perception of truth, and thought, can nowhere be more clearly seen and confirmed than in the lungs and the structure thereof. These, therefore, must be briefly described. After birth, the heart discharges the blood from its right ventricle into the lungs; and, after passing through these, empties it into its left ventricle; and so opens the lungs. This it does through the pulmonary arteries and veins. The lungs have bronchial tubes which branch out, and finally terminate in air-cells, into which the lungs admit air and so breathe. Around the bronchial tubes and their branches there are arteries and veins, called bronchia, rising from the vena azygos or vena cava and from the aorta. These arteries and veins are distinct from the pulmonary arteries and veins. These facts make it plain that the blood flows into the lungs by two ways and flows out of them by two ways. This enables the lungs to breathe at a different rate from the heart's beat. It is well known that the alternate motions of the heart and of the lungs respectively do not act as one. Now since there is a correspondence of the heart and lungs with the will and understanding, as was shown above, and since conjunction by correspondence is such that as one acts, so the other acts, it can be seen, by the influx of blood from the heart into the lungs, how the will flows into the understanding, and affects the things mentioned just above, concerning affection for and perception of truth, and concerning thought (n. 404). Correspondence has revealed to me this and many other things concerning them, which cannot be described in a few words. Since love or the will corresponds to the heart, and wisdom or the understanding corresponds to the lungs, it follows that the blood vessels of the heart in the lungs correspond to affections for truth, and the branches of the bronchia of the lungs to perceptions and thoughts from those affections. Anyone who explores all the tissues of the lungs from these beginnings and makes the analogy with the love of the will and with the wisdom of the understanding, will be able to see as in a certain image the things mentioned above (n. 404), and so be confirmed in faith. But since the facts of anatomical knowledge concerning the heart and lungs are known to a few, and confirming anything by the unknown leads to obscurity, I refrain from further demonstration of the analogy.