Ok, how about this one:
"A defining feature of the 1986 reform was the broadening of the tax base and the lowering of tax rates, and it is widely believed that these changes enhanced economic efficiency. High tax rates (whether the base is income or consumption) exacerbate the distortions that taxes invariably create. Moreover, distortions arise when similar activities are subject to different tax treatments. Such distortions reduce economic efficiency as households and businesses respond to the tax code rather than to underlying economic fundamentals. Lowering tax rates by broadening the tax base generally will reduce the costs of such distortions, which are approximately proportional to the square of the tax rate. Over the years, economists have disagreed about the size of the efficiency gains that might be achieved from a broader base and lower rates, but there can be little doubt regarding their positive effect."
-- Alan Greenspan
http://www.federalreserve.gov/boarddocs/testimony/2005/20050303/
