And they sat before him, the firstborn according to his birthright, and the youngest according to his youth: and the men marveled one at another.
Read Chapter 43
Ephrem The Syrian
Joseph began to make his brothers sit down as if around his [divining] cup; the elder according to his status as elder and the youngest according to his youth. It is amazing that his brothers did not recognize him: not by the money in their provisions when they went home the first time, not when Joseph had Simeon bound, not when he asked about his old father when they brought Benjamin back, not when they were accused of cheating, not from the fact that he made them stay in his house and blessed Benjamin, not even from the fact that he knew the names of all of them. This was all the more [amazing] since even his appearance was so similar. Even if his majesty had deluded them, his dreams should have jarred their memory. Although they did not recognize Joseph because of his majesty, his rank and his angry tongue, it was nevertheless because of the Lord that he remained hidden from them until his dreams should be fulfilled in them who had sold him in order to render them false.
They sat. This posture is more ancient than that of lying down at table. The Hebrews adopted the latter, from the Persians, during the captivity, Esther i. 6, and vii. 8.
We have at least no earlier vestige of this custom in Scripture. (Calmet)
Very much: as they were placed in that order by the steward. They knew not how he could so exactly discover who was born first, as there was so short an interval between the births of many of them. (Haydock)