In the Book of פרקי אבות , Sayings of the Fathers, there is a Mishna that states: אל תסתכל בקנקן אלא במה שיש בו, “Look not on the jar but what is in it; there may be a new jar that is full of old wine and an old one in which is not even new wine.” (Avot 4,20) Old wine is superior to new wine. The meaning is, of course, that we should not depend on outward appearances but look closely at the true nature of what we observe.
This statement comes to mind in connection with what Yosef sent his father when he invited him to come to Egypt. He knew his father would be shocked to see him dressed as an Egyptian, since his high governmental position required it. He wanted him to know that inwardly Yosef was still loyal to his Jewish tradition which he acquired from his father.
Yosef, therefore, sent his father: עֲשָׂרָה חֲמֹרִים נֹשְׂאִים מִטּוּב מִצְרָיִם, “…ten donkeys laden with the best of Egypt…” (Gen. 45,23) What exactly was it that he sent? The Talmud tells us: שלח לו יין ישן, שדעת זקנים נוחה הימנו, “he sent him old wine which old men find very comforting.” (Meg. 16b)
When Yosef sent him wine he was alluding to the statement quoted above. He did not want Yaakov to look at his outward appearance when they met. He wanted to assure him that inwardly he was still Jewish and was still living up to the traditions he had been taught.