In today's Wall Street Journal, "Notable & Quotable" excerpts reason's 1975 interview with Ronald Reagan:
If you analyze it I believe the very heart and soul of conservatism is libertarianism. I think conservatism is really a misnomer just as liberalism is a misnomer for the liberals-if we were back in the days of the Revolution, so-called conservatives today would be the Liberals and the liberals would be the Tories. The basis of conservatism is a desire for less government interference or less centralized authority or more individual freedom and this is a pretty general description also of what libertarianism is.
The full, fascinating interview is available here.