I did not come from an ...

I did not come from an academic background. My father was a smart man, but he had a fifth-grade education. He and all his friends were plumbers. They were all born around 1905 in great poverty in New York City and had to go to work when they were 12 or 13 years old.
 Leonard Susskind

Quotes from the same author

[Richard Feynman] truly believed that if you couldn't explain something simply, you didn't understand it.
 Leonard Susskind