1387. I have several times conversed about perception with those in the other life who, while they lived in the world, had regarded themselves as able to penetrate and understand all things; telling them that angels perceive that they think and speak, and will and act from the Lord. But still they could not conceive what perception is, but supposed that if all things were to inflow in this way, they would be bereaved of all life; because in that case they would think nothing from themselves, or from what is their own; and in this they had made life to consist; and that in that case it would be another who was thinking, and not themselves; so that they would be mere organs devoid of life. But they were told that between having perception, and not having it, the difference of life is like that between light and darkness; and that men first begin to feel alive when they receive such perception; for then they live from the Lord, and also have what is their own, which is given together with all happiness and delight. It was also shown them by varied experience how the case is with perception, and at the time they acknowledged the possibility of it; but after a while they again did not know, doubted, and denied. From this it has been made evident how difficult it is for man to comprehend what perception is.