That Yochanan b. Zakai knew the discussions of Abaye and Rava who lived after him..... what sort of explanations exist on the anachronism of this statement?
hg schild, ny usa
1. RASHI DH HAVAYOS writes that R. Yochanan ben Zakai thought about all the matters which Abaye and Rava were later on doubtful about. R. Yochanan explained logically all of Abaye and Rava's questions but later on, in the times of the Amoraim, R. Yochanan's teachings were forgotten, so Abaye and Rava had to reconsider these discussions.
2. RITVA explains further that this refers to all of the questions, answers and doubts of Abaye and Rava which were not clear to them because they did not reach the depths of the Talmud in the way that the earlier Sages did. This is called a "small matter" because it arose due to their lack of knowledge and therefore it was less than the wisdom of the Mishnah itself, which preceeded them. However the discussions of Abaye and Rava are greater than all other wisdom of the nations. They were only termed a "small matter" in comparison with the wisdom of the earlier generations of Chachmei Yisroel.
(The above explanations are based on the concept of Yeridas ha'Doros: the further away we get from the time of receiving the Torah on Har Sinai, the lower the Torah understanding of the generations falls.)
KOL TUV
D. Bloom