Incidentally, a lot of the songs were used in "call and response" style--this made them easy to teach while they were being sung--there are a good number of live recordings from the "good old days" in which songs are taught to the audience during a performance--this side of the audience sings "this little light of mine" and this side sings "I'm gonna let it shine", for example.

The best songs used powerful images, simply expressed, with lots of repetition. There weren't very many of them, but they were easy to learn, and easy to sing along with the first time you heard them. In fact, they were hard to forget--