We the people, in order to . . . insure domestic Tranquility. . .

Insure
v 1. To make sure or secure; as, to insure safety to any one. [1913 Webster]
2: be careful or certain to do something; make certain of something;
Tranquility
n 1: a disposition free from stress or emotion
2: a state of peace and quiet

Despite the current focus of the Religious Right, I doubt the Founding Fathers were referring to the state of our households with their third constitutional goal.
The domestic tranquility they were concerned about was the relationships between the Colonies.
Europe had just spent the better part of the last century in a series of domestic squabbles. The Austrian Succession, the Seven Years War, the Great Northern War - all these, and several others, were little territorial struggles between neighbours. Prussia trying to grab Silesia, Austria grabbing Milan - this was what the rulers of the time did to improve their economy and prestige. Easier to seize a good agricultural area than to create one.
The Founding Fathers wanted to avoid having the Thirteen Colonies become thirteen warring states, expending their strengths in attempts to become number one. The Constitution was meant to create a central government in which all states would be equal.
Today, of course, the electoral votes of three states are crucial, and many states get attention according to the number of votes they can bring to the table. Texas, New York, California, and, yes, Ohio and Florida get a lot more attention (ie money) than North Dakota and Oregon.
This was never the Framer's intent. They wanted a united country, not an eternal squabble for pork barrel dollars and Congressional attention.
Pity. Another goal down the drain.