If any of us wish to understand ourselves, our nation, or our world, we must, as Baldwin wrote, understand our history. What is writ large in society is also writ small in the sciences. So to understand Psychology, we must understand its history.
Everybody thinks they are an expert on parenting and childcare. After all, they were children once and often times (but not always) they have been parents. This is like thinking that you are a doctor, because after all you do have a body and you have been sick before.