[157] And here any one may reasonably express a doubt how it is possible for any one to laugh when laughter had not as yet come among one branch of the creation; for Isaac is laughter, who, according to the account under our consideration at present, was not yet born. For just as it is impossible to see without eyes, or to hear without ears, or to smell without nostrils, or to exert any other of the external senses without the organs adapted to each respectively, or to comprehend without the reason, so also it is not likely that a person can have laughed, if laughter had not as yet been made.