In Federalist 51, Madison proposes that the interior structure of the government itself must be responsible for equally dividing the power among the branches because the employment of an exterior body would be inadequate. He said that each branch should check and balance out the other two. This process will, and has succeeded because the branches are familiar with one another, but Madison cautions that each branch needs to have a will of its own and needs to be as limited involved in or dependent upon the others as possible. This allows for the power and appointments of each branch to be drawn from the people, rather than the other branches.
Madison also discusses the danger of relying on the people in government to control the people in government. Politicians are imperfect humans and have flaws which, in the proposed system of checks and balances, will be precariously balanced by the flaws of the other politicians.
There will be a branch that has more responsibility and power to check the others, and that is the legislative branch. Madison solved the problem of inequality by dividing it into two houses.
Madison's system of having the government check itself provides a double security for the rights of the people. The different governments control each other and are controlled by themselves.
In history books, checks and balances are still described as the way branches of our government is kept from becoming too powerful. It seems as though Madison's system is still functioning and effective today.