What does it take to create a work of art with another person? Talent, inspiration, hard work, patience. But the most important part of the equation may be whether two people hit it off, the spark of personalities on the same wavelength. James Lapine found his best collaborator in Stephen Sondheim, one of the greatest theater composers ever. Lapine was 20 years younger than Sondheim. They both liked to smoke pot. Their first work together turned out to be a Broadway show called Sunday in the Park with George which wound up winning a Pulitzer Prize. They went on to create Into the Woods and Passion. I talk to James Lapine about his relationship with Sondheim, who died suddenly last year, and the art of thinking outside the box.