Explanation: One of Hitler's reasons for invading Europe was to get more Lebensraum, or Living Space, Breathing Room, etc.
the columbian exchange introduced the Europeans and people in the Americas new types of crops, such as potatoes, sweet potatoes and cassava
The meaning of this quote "A leader is best when people barely know he exists; when his work is done, his aim fulfilled, they will say; we did it ourselves" means if the leader is unknown to many people once he has finished or achieved a remarkable goal other people (such as Laozi) can steal the glory and be remembered for something they didn't do.
