In 1951, he returned to Germany to find out what had made Nazism possible.… When Mayer returned home, he was afraid for his own country. He felt … that under the right conditions, he could well have turned out as his German friends did. He learned that Nazism took over Germany not ‘by subversion from within, but with a whoop and a holler.’”
Now we just need to get "they thought they were free“ to the top of the list
https://www.amazon.com/dp/B01FKSNOSG/ref=cm_sw_r_tw_apa_i_lIO.FbZH1J8CK