This is why Romney is taxed at a lower aggregate rate than you are, because a BIG chunk of his income comes from investments, not from punching a clock on a job every day.
"One of the most basic principles in economics is that the taxation of capital income is inefficient. Taxes on interest, dividends, and capital gains represent a sort of “double taxation”, of wage income. For some reason many people have difficulty grasping this concept, and one often sees even Nobel Prize-winning economists talking about “income inequality” using data that includes both wage and capital income. This makes about as much sense as adding up blueberries and watermelons and calling it the 'number of units of fruit' "
The quote is from this article:
which does a good job of explaining this, and even has a compelling argument for reducing income on investments to zero as the results of that work has already been taxed.