Moses [Moshe] received the Torah from Sinai and gave it to Joshua. That is how Pirkei Avot begins.
The Gra explains "he gave it to Joshua" comes from the verse ונתת מהודך עליו and you will place from your glory upon him. This is because it never says anywhere in the Torah that Moses gave the Torah to Joshua. [Rather it says he wrote the Torah and gave it to the priests.] Rather the Mishna has to be referring to the אור אין סוף the Divine light.
The idea here is this. The way I explained this a few years ago was in reference to the First Temple.
In the period of the First Temple, the Divine light was shinning without differentiation. When the Temple was destroyed most of it went to Athens and only מלכות שבמלכות royalty of royalty remained in Israel. This is how I used to explain this idea of how the light can shine on a person or a people but it not becoming differentiated until later.
This is also how to understand how the Torah was given to Moshe. It means the undifferentiated light.
The idea here is this. The way I explained this a few years ago was in reference to the First Temple.
In the period of the First Temple, the Divine light was shinning without differentiation. When the Temple was destroyed most of it went to Athens and only מלכות שבמלכות royalty of royalty remained in Israel. This is how I used to explain this idea of how the light can shine on a person or a people but it not becoming differentiated until later.
This is also how to understand how the Torah was given to Moshe. It means the undifferentiated light.