As noted in the comment titled "Gerald Ford," a basic web search on key phrases from the quote shows that this has been widely (though unreliably) attributed to Thomas Jefferson. A useful tip-off that this is questionable, besides the sound of the language, is that none of the Jefferson attributions cite a source. This is an example of what has been called the "echo effect" of the web (though it is certainly not new to this medium), whereby faulty information gets repeated , especially when it suits an ideological purpose, without fact-checking. Eventually you have dozens of websites, filling the first several pages of search results, repeating baseless information.
The Gerald Ford attribution, on the other hand, didn't appear until maybe the fourth page of results, but does provide a specific source for the quote. Final verfication entails checking the text of Ford's speech in The Congressional Record for August 12, 1974, or in Public Papers of the Presidents: Gerald Ford. Both could be found using the WorldCat record just linked to, or by finding a Federal Depository Library near you.
The quote appears on page eight of Public Papers of the Presidents: Gerald R. Ford, 1974:
Whether we like it or not, the American wage earner and the American Housewife are a lot better economists that most economists care to admit. They know that a government big enough to give you everything you want is a government big enough to take everything you have.
Note that Ford does not say "as Thomas Jefferson said" or anything like that. It would require some archival digging to uncover which speechwriter came up with the sentence, but it was not Jefferson.
