"Blood alone moves the wheels of history." - Martin Luther

I think this quote means that we only remember violence, sacrifice and war about the past. And that the most significant things that people learn about the past is related to war. But in recent times this isn't necessarily true for example their have been thousands of inventions that have been remembered for their importance over time like the invention of plastic, cars, planes, the internet, phones etc... and they are not related to war. But it does seem that the most significant events in history relate to sacrifice and war.