2072. And laughed. That this signifies the affection of truth, may be seen from the origin and essence of laughter, for its origin is nothing but the affection of truth, or else the affection of what is false, from which come the gladness and merriment that in laughter display themselves in the face, which shows that the essence of laughter is nothing else. Laughter is indeed an external thing that belongs to the body because to the face; but in the Word interior things are expressed and signified by exterior things; just as all the interior affections of the mind are expressed and signified by means of the face, interior hearing and obedience being signified by the ear, interior sight or understanding by the eye, power and strength by the hand and arm, and so on, and in the same way the affection of truth by laughter.
 In man's rational there is truth, which is its chief characteristic, and there is also the affection of good, but this is in the very affection of truth as its soul. The affection of good which is in the rational does not display itself by means of laughter, but by means of a certain joy and consequent pleasurable delight which does not laugh; for in laughter there is usually something that is not so good. The reason why truth is the chief characteristic in man's rational, is that the rational is formed by means of the knowledges of truth, for by no other means can anyone ever become rational. The knowledges of good are truths, equally as much as are the knowledges of truth.
 That "laughter" here signifies the affection of truth, may be seen from its being related that Abraham laughed; and in like manner Sarah, both before Isaac was born, and afterwards; and also from Isaac's being named from "laughter," for the word "Isaac" means "laughter." That Abraham laughed when he heard about Isaac, is evident from this verse, for it is said that Abraham laughed when he heard about a son from Sarah. That Sarah also laughed before Isaac's birth, when she heard from Jehovah that she should bear a son, is told in the words, "When Sarah heard at the door of the tent, Sarah laughed within herself, saying, After I am grown old shall I have pleasure? and my lord old? And Jehovah said unto Abraham, Wherefore did Sarah laugh, saying, Shall I of a surety bear a child, and I am become old? Sarah denied, saying, I laughed not; for she was, afraid. And He said, Nay, but thou didst laugh" (Gen. 18:12, 13, 15). And later, when Isaac had been born, "Abraham called the name of his son Isaac" (meaning "laughter"); and Sarah said, "God hath made laughter for me; everyone that heareth shall laugh with me" (Gen. 21:3, 6). Unless "laughing" and the name "Isaac," meaning "laughter," involved such things, these matters would never have been related.