Where you go to have your Hebrew beliefs and
philosophies freshened up and more-solidly
established in your mind, after the decades of unavoidably associating with Gentiles has worn and numbed said basic values.
Doc Brown told Marty that he'd gone to a rejewvination clinic, but I am at a
bit of a loss as to why he would feel any need to do that, since there was never any mention of his having
Semitic/Hasidic
ancestry or traditions.