Deuteronomy (31:10-13) tells us to read the Torah once every seven years during the festival of booths. I also know that about a thousand years ago, a Rabbi decided that the people were forgetting what the Torah said so he caused it to be divided into the weekly portions. What I don’t know is the Rabbi’s name. Do you? Please let me know.
The basis of your question is not quite correct. The Torah does say to read part of the Torah publicly during the festival of Succot, but this was done by the King, and is not at all connected to our weekly Torah reading in Synagogue.
The Talmud tells us that Moses instituted the custom of reading the Torah three times every week, and in the time of Ezra this was formally codified to be a Torah reading every Monday and Thursday as well as Shabbat. The division of the Torah into weekly portions
goes back at least 2000 years, though there was a difference of custom between Israel and Babylon. In Israel they read the Torah in a 3 year cycle, whereas in Babylon they read the entire Torah every year (the custom we follow nowadays). I don’t believe that any single Rabbi made these divisions, nor that it was because people were forgetting the Torah.
There is a famous Rabbi, called Rabbi Yehuda HaNassi, who compiled the Mishna around the year 200. This is the first codification of the Oral Law, which had been given to Moses at Mount Sinai. Although it was supposed to remain as an oral tradition, passed down from teacher to student, Rabbi Yehuda realised that after the destruction of the Second Temple, and as a result of the dispertion of the Jewish people, this Oral Law was at risk of
being forgotten. Therefore he wrote it down (cryptically) as the Mishna. Later this was elaborated on and became the basis of the Talmud and other books.
Regards
Rabbi David Sedley