According to the explanation of the Constitution on the official White House website, the Constitution was a product of its time in that it addressed various contemporary political concerns, such as the weakness of the Articles of Confederation. The integration of checks and balances into the political system was also an alternative to an overwhelmingly strong central government, such as that of the British monarch and Parliament.
Ratified in 1781, the Articles of Confederation gave the only branch of the national government, the Congress of Confederation, the power to wage war, conduct foreign affairs and regulate the economy. However, the states were largely independent entities, and without authority to enforce requests to the states, the Congress had little power. The writers of the Constitution were tasked with creating a national government powerful enough to act, but not so powerful as to restrict the rights of the states. To accomplish this, they devised three separate branches of government, each with limitations to its power, so that no one branch could attain supremacy over the others.
Because the states varied greatly in size, there was sharp debate about whether the legislative branch should vote based on the population of the states or whether each state should have one vote. In the end, they compromised by dividing the legislature into two branches. The House of Representatives would vote according to population, while the states would have equal votes in the Senate. To further balance the system, the Electoral College would elect the President, and the judicial branch would remain completely independent of the other branches of government. Any power not specifically delegated to the federal government was reserved for the states. This elaborate system of limitation of governmental powers was a direct result of the revolution of the states against the British monarchy and their desire to retain their freedom.