"It is not very unreasonable that the rich should contribute to the public expense, not only in proportion to their revenue, but something more than in that proportion."
Adam Smith, The Wealth of Nations, Book V, Chapter II.
Another excellent Smith quote with which I fully agree, and one often overlooked by avowed Smith fans, though I don't see it's immediate applicability to the issue at hand.
Currently only high revenue is taxed (at a personal level). Wealth isn't taxed. At least not in the UK. I guess in the U.S income tax deductions mean it's skewed a little more to profit rather than revenue.
Adam Smith, The Wealth of Nations, Book V, Chapter II.