What principle of the government presented by the U. S constitution is Montesquieu describing

Montesquieu is describing the "Separation Of Powers" which is important because it states that government should be split up into 3 branches the Legislative (which is Congress), The Executive (the President), and the Judicial (the Supreme Court). Montesquieu wanted this so that power could be divided equally and so that it wasn't just one big Government with all the power.