298. The spirits who are with man, both those conjoined with heaven and those conjoined with hell, never flow into man from their own memory and its thought, for if they should flow in from their own thought, whatever belonged to them would seem to man to be his (see above n. 256). Nevertheless there flows into man through them out of heaven an affection belonging to the love of good and truth, and out of hell an affection belonging to the love of evil and falsity. Therefore as far as man's affection agrees with the affection that flows in, so far that affection is received by him in his thought, since man's interior thought is wholly in accord with his affection or love; but so far as man's affection does not agree with that affection it is not received. Evidently, then, since thought is not introduced into man through spirits, but only an affection for good and an affection for evil, man has choice, because he has freedom; and is thus able by his thought to receive good and reject evil, since he knows from the Word what is good and what is evil. Moreover, whatever he receives by thought from affection is appropriated to him; but whatever he does not receive by thought from affection is not appropriated to him. All this makes evident the nature of the influx of good out of heaven with man, and the nature of the influx of evil out of hell. 299. I have also been permitted to learn the source of human anxiety, grief of mind, and interior sadness, which is called melancholy. There are spirits not as yet in conjunction with hell, because they are in their first state; these will be described hereafter when treating of the world of spirits. Such spirits love things undigested and pernicious, such as pertain to food becoming foul in the stomach; consequently they are present with man in such things because they find delight in them; and they talk there with one another from their own evil affection. The affection that is in their speech flows in from this source into man; and when this affection is the opposite of man's affection there arises in him sadness and melancholy anxiety; but when it agrees with it it becomes in him gladness and cheerfulness. These spirits appear near to the stomach, some to the left and some to the right of it, and some beneath and some above, also nearer and more remote, thus variously in accordance with their affections. That this is the source of anxiety of mind has been shown and proved to me by much experience. I have seen these spirits, I have heard them, I have felt the anxieties arising from them, and I have talked with them; when they have been driven away the anxiety ceased; when they returned the anxiety returned; and I have noted the increase and decrease of it according to their approach and removal. From this it has been made clear to me why some who do not know what conscience is, because they have no conscience, ascribe its pangs to the stomach.{1}