Near the beginning of the Torah, in parshat Breishit we see that G-d exiled Adam from the Garden of Eden because he was worried that Adam would eat from עץ החיים - the tree of life (Ber 3,23).
וַיֹּ֣אמֶר ה"א הֵ֤ן הָֽאָדָם֙ הָיָה֙ כְּאַחַ֣ד מִמֶּ֔נּוּ לָדַ֖עַת ט֣וֹב וָרָ֑ע וְעַתָּ֣ה ׀ פֶּן־יִשְׁלַ֣ח יָד֗וֹ וְלָקַח֙ גַּ֚ם מֵעֵ֣ץ הַֽחַיִּ֔ים וְאָכַ֖ל וָחַ֥י לְעֹלָֽם׃
And the LORD God said, “Now that the man has become like one of us, knowing good and bad, what if he should stretch out his hand and take also from the tree of life and eat, and live forever!”
Yet, Proverbs 3:18 refers to the Torah as an עץ חיים.
So, it seems that the Torah forbade man to use it or learn from it. Essentially, the Torah forbade itself. Why?