Why did thomas jefferson support the louisiana purchase?

The Louisiana Purchase was the acquisition of the Louisiana territory by the United States from France in 1803. The U.S. paid fifty million francs and a cancellation of debts worth eighteen million francs for a total of sixty-eight million francs. The Louisiana territory included land from fifteen present U.S. states and two Canadian provinces. The territory contained land that forms Arkansas, Missouri, Iowa, Oklahoma, Kansas, and Nebraska; the portion of Minnesota west of the Mississippi River; a large portion of North Dakota; a large portion of South Dakota; the northeastern section of New Mexico; the northern portion of Texas; the area of Montana, Wyoming, and Colorado east of the Continental Divide; Louisiana west of the Mississippi River; and small portions of land within the present Canadian provinces of Alberta and Saskatchewan. Its non-native population was around 60,000 inhabitants, of whom half were African slaves.

I'm pretty sure that's called a volcano