The Posuk says
ושמרתם ועשיתם כי היא חכמתכם ובינתכם לעיני העמים
To which Rashi Comments:
'ושמרתם' זו משנה
Reb Moshe Feinstein in Darash Moshe asks why is it that the torah is referd to as a watching?
He answers that Torah is something that must be learnt by a Rebbi it must be watched in a sense if you use your own logic you are liable to make errors in judgment which would put the whole Torah in question. Therefore it must be watched given over from a Rebbi to talmid as if left to ones own intellect it may happen as that what happened to the generation of Enosh who came to the understanding that they should not worship g-d but his servants in the Heavens as they listen to their own intellect and not their elders Adam and Sheis.