Answer:
Throwing away a part of yourself means that you are throwing away what made you who you are today. In other words, if you "threw away a part of yourself" you'd be ignoring what you've endured/experienced to get to where you are today. Similarly, if you throw away our history, that would be discarding everything out nation went through to get to the place that we are today. We wouldn't be able to appreciate how far we've come if we threw away all our history.
Hope this helps!