What kind of tax would Adam Smith have approved of?

Cato:

Most of the Founding Fathers were students of the Scottish Enlightenment, and the most influential book on their thinking was Adam Smith's The Wealth of Nations, published in 1776. (Smith and Ben Franklin were personal friends.) In his section on taxation, Smith said: "The subjects of every state ought to contribute towards the support of the government ... that is, in proportion to the revenue which they respectively enjoy under the protection of the state." In modern parlance, Smith was endorsing a proportional or "flat tax," or VAT, or sales tax. Smith went on to say, "The tax which each individual is bound to pay ought to be certain, and not arbitrary. Where it is otherwise, every person subject to the tax is put more or less in the power of the tax gatherer. ..." Finally, Smith noted: "Every tax ought to be so contrived as both to take out and to keep out of the pockets of the people as little as possible, over and above what it brings into the public treasury of the state." The income tax and IRS fail on all accounts, and neither Smith nor the American Founders would have approved.