How does the authors mixture of slang colloquialism and pop culture references dropouts, hippies, phonies plumb lazy with his formal tone and language contribute to the texts effectiveness?

Ifound this on google “preview — long walk to freedom by nelson mandela. “i am fundamentally an optimist. whether that comes from nature or nurture, i cannot say. part of being optimistic is keeping one's head pointed toward the sun, one's feet moving forward.” i hope this you for what your looking for.