Explain what montesquieu means when he writes every man invested with power is apt to abuse it and to carry his authority as far as it will go?

In his book, "The Spirits of the Law", Montesquieu writes this pasage advocating for the separation of powers within the government.

He explains that political liberty can only exist when there is no abuse of power, and history has shown a repetitive abuse of power by the man who held it.

Therefore, Montesquieu calls for a system of checks and balances in which no man is compelled to do what the law does not oblidge him nor does he have to refrain from doing what it allows.

it was certainly a debatable decision, mainly because it was based primarily on political - and not on legal or social - views. since the congress at that time was led by members of the republican party, and the territory that the tribes wanted to turn into an exclusively indian state was predominantly democratic, the proposal (as expressed in the constitution) did not succeed, but the constitution itself proved to be of crucial importance in the creation of the state of oklahoma, and, most importantly, it guaranteed the involvement of representatives of the indian tribes in the government of the future joint state.  

as a member of congress, i would have voted to ratify the constitution, or at least to have it tabled. ignoring it was an interested and partial decision.