Midrasch zu Divrej Hajamim II 21:3

"Simon, my son, should be the Chacham." What did he mean by this? He means thus: although Simon, my son, is wise, nevertheless Gamaliel, my son, should be conferred with the dignity of Patriarch. Levi asked: "Why was it necessary to give such an instruction [since he was the oldest one?"] Said R. Simon b. Rabbi: "It was necessary for thee and for thy lame foot." Why did not R. Simon understand the question. Is there not a passage (II Chr. 21, 3) But the kingdom gave he to Jehoram; because he was the first born? There it was different, because he was able to fill out the place of his father in every respect; but Gamaliel was not able to fill out the place of his father. If so, then why did Rabbi give instructions to make him the Patriarch? Rabbi's reason was because, granted that he was not able to fill his father's place in wisdom, nevertheless in fearing God he did fill his father's place. "Chanina b. Chama should be the head of the academy." R. Chanina, however, did not accept the position, because R. Appas was two and a half years older than he. Therefore R. Appas became the head. R. Chanina, nevertheless, remained outside. Levi then joined R. Chanina as an associate to him, and when R. Appas died, which caused the elevation of R. Chanina to the chief of the academy, Levi, not having anyone to join him, left the land of Israel and emigrated to Babylonia, and this is what the people informed Rab. "A great man happened to come to Nehardea, lame on one leg, and expounded that a woman is permitted [on the Sabbath] to take a stroll, while bearing a wreath on her head." Rab then said: "This proves that R. Appas died and R. Chanina became the chief of the academy, hence Levi did not have anyone to associate with him and therefore came here." Why not say that R. Chanina died, so R. Appas remained as before, but Levi merely lost his associate and was compelled to come to Babylon? If you wish I will explain that Levi would have subordinated himself to the control of R. Appas [and his refusal was chiefly because he desired to be an associate to R. Chanina]; and if you wish I will say since Rabbi ordered that R. Chanina should become the chief of the academy, it became impossible that he should die and not become a chief, for it is said (Job. 22, 28) And if thou decree a thing, it will be fulfilled unto thee. But why did not Rabbi appoint as the chief of the academy R. Chiya, who was the oldest? Because R. Chiya had been dead already. But do we not find that R. Chiya said: "I saw the grave of Rabbi upon which I shed tears"? This was the reversed condition [that Rabbi saw R. Chiya's grave and shed tears on it.] But has not R. Chiya said that the day on which Rabbi died, holiness was abolished? This was taught in the reversed way. But again, is there not a Baraitha that when Rabbi became ill, R. Chiya entered to visit him and found him weeping, whereupon R. Chiya said to him: "Why art thou crying? Are we not taught in a Baraitha that when one dies while laughing it is a good omen, but when one dies while crying it is a bad omen, dying with his face upward, it is a good omen; but with his face downward, it is a bad omen; with his face towards the wall, it is a bad omen; but with his face towards the people, it is a good omen. If one's face turns green after death, it is a bad omen; but if one's face looks reddish or yellow, it is a good omen. If one dies on the Sabbath eve, it is a good omen; but if one dies on the termination of the Sabbath, it is a bad omen. If one dies on the eve of the Day of Atonement, it is a bad omen; but if one dies on the termination of the Day of Atonement, it is a good omen. If one dies of an intestinal sickness, it is a good omen, because the majority of the righteous die of an entrail sickness." Whereupon Rabbi answered him: "I am weeping because of the Torah and the meritorious deeds which I will not be able to perform." [Hence we see that R. Chiya was alive when Rabbi died.] If you wish, you may reverse the above Baraitha, and if you wish you may say that it is not necessary to reverse the Baraitha; but since R. Chiya devoted his time to important meritorious deeds, Rabbi thought it is better not to disturb him.