Oh, how the party has changed. 

At a moment when the Republican Party has shifted dramatically from its Reaganite roots, I talk with Washington Post columnist Max Boot, whose definitive biography of Ronald Reagan arrives with particular resonance.

Through a decade of research, Boot reveals a pragmatic leader who would likely be puzzled by today's GOP—a president who supported immigration reform, worked with Gorbachev to reduce nuclear weapons, and prided himself on compromise, getting "80 percent of what he wanted" rather than demanding everything. Boot shares with me a fascinating exploration of Reagan's true legacy.