Breaking Through

 וְלֹא⁠־יָכֹ֣ל מֹשֶׁ֗ה לָבוֹא֙ אֶל⁠־אֹ֣הֶל מוֹעֵ֔ד כִּֽי⁠־שָׁכַ֥ן עָלָ֖יו הֶעָנָ֑ן וּכְב֣וֹד י״י֔ מָלֵ֖א אֶת⁠־הַמִּשְׁכָּֽן.  Moshe could not enter due to the presence of the cloud and the kavod of Hashem present.  Why specifically at this time after the completion of the Mishkan, the place of the ultimate connection between Hashem and Klal Yisrael is there a barrier, are the doors shut?  

Rebbe Nachman says on the possuk (Shemos 20:18) וַיַּעֲמד הָעָם מֵרָחֹק וּמשֶׁה נִגַּשׁ אֶל הָעֲרָפֶל אֲשֶׁר שָׁם הָאֱלֹקִים that when wants to rise up to a greater level of service in Hashem, there are road barriers that stand in the way.  One who is afraid, the עם, feels distant due to the impasse but משה, one with דעת, recognizes that it is in the barrier where one finds Hashem.  It is only by fighting through the hardship that one can achieve a greater closeness to Hashem.  That is what Rashi (Shemos 24:18) means that at Mattan Torah a path was made for Moshe to enter though the smoke.  Once one puts in effort to go through the difficulty, it parts and one finds Hashem there.  This may be why specifically at this great pinnacle ,the completion of the Mikdash, again there has to be a barrier to demonstrate to tap into the power of the Mikdash you must go through this final barrier.   In order to grow you must go through barriers.