I just stumbled across a fascinating web resource of quotations from Thomas Jefferson talking about taxation. It turns out that Jefferson clearly favored progressive taxation.
I approved from the first moment of... the power of taxation [in the new Constitution]. I thought at first that [it] might have been limited. A little reflection soon convinced me it ought not to be.
Taxes should be proportioned to what may be annually spared by the individual.
Another means of silently lessening the inequality of property is to exempt all from taxation below a certain point, and to tax the higher portions of property in geometrical progression as they rise.
the farmer will see his government supported, his children educated, and the face of his country made a paradise by the contributions of the rich alone, without his being called on to spend a cent from his earnings
Interestingly, the quotations give us a Jefferson who supports tariffs as the primary source of government revenue because imports are luxury goods used by the rich. I didn't know that.
Since quasiliberarian conservatives like to claim Jefferson as the great minarchist of the Founders, I suspect that this will come in handy. (Apropos of which, if you haven't seen it, dig a quote I blogged a while back about John Locke supporting redistribution of wealth.)