I believe Jefferson said something along the lines of blood needing to be shed roughly every generation so we don't allow the problems that we are currently living with today flourish.
Edit: "The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants. It is its natural manure" Thomas Jefferson, ~1787
Edit: "The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants. It is its natural manure" Thomas Jefferson, ~1787