Book 3 · Section 55

(55) Why did Abraham fall on his face and laugh? (#Ge 17:17). Two things are indicated by his falling on his face. One an act of adoration on account of the excess of his divine ecstacy; the other that it corresponds to and is suitable to the aforesaid harmony, by which the intellect has confessed that God alone exists in a continual and unvarying existence. But those creatures which owe their existence to creation and generation, all are subject to changes in time; for they fall to a certain extent, inasmuch as they are accustomed to rise up, and to be corrected in accordance with their original appearance. And it was very natural for Abraham to laugh at the promise, as he was then filled with the great hope that the things which he expected should be accomplished, especially because he had received a manifest revelation from that appearance, by which he became more thoroughly acquainted with him who exists for everlasting without variation, and with him also who is continually stooping and falling.