Instead Of The Beis Hamikdash

The gemara says that from the time the beis hamikdash was destroyed all Hashem has in the world is the 4 amos of halacha. This means apparently that the SOLE SUBSTITUTE for the beis hamikdash is learning halacha [gemara, rishonim and achronim is also halacha - not always halacha lamyseh but halacha]. The beis hamikdahs is השראת השכינה - Hashem's presence dwelling among us and so too when one learns the שכינה descends.