Do you Agree or disagree with Jefferson's statement that "Men by their constitutions are naturally divided into two parties. Can you provide your best reason for holding that position and relate it to the emergence of Whigs and Democrats as representatives of the nation's first two-party political system

According to Jefferson himself, you could divide man in two kinds:

1) Those who did not trust people or feared them. Those people, supposedly, wished to prevent them from having powers by giving that power to a specific class that would hold the responsibility of watching over the people and the nation.

2) Those who are confident in the people and their individual liberties and consider them mostly honest and good people. In that case, there would be no need to give great powers to a higher class. In fact, that would be counterproductive to their ideals.

You will find those two lines of thinking in pretty much every country and every culture. They are considered often as Left or Right, Progressive or Conservative, Liberal or Socialist and so on.

That showed up quickly in the USA since when the Whigs party emerged, it did as opposition to the Democrat Party. Showing an early duality from the beginning of the American Democracy. And even if you have a multiparty system like other countries, you can easily find them dividing generally in two sides that internally agree with MOST issues but disagree fundamentally in many with the opposition.