Stephen Colbert doesn't hide his regard for Stephen Sondheim when he welcomes him to The Late Show as "the greatest composer and lyricist in the history of the American theatre." The Tony and Pulitzer-winning musical theatre legend appeared on the nightly talk show September 15.

In the brief (but jam-packed!) interview, Sondheim and Colbert discussed the composer's start in musical theatre as a mentee of Oscar Hammerstein II, his Sunday in the Park With George collaborator James Lapine's new book Putting It Together, the upcoming Broadway production of Company, and the upcoming film West Side Story. The latter two productions come highly recommended by the composer. "I don't usually tout my own stuff, but I urge everybody here to see it," Sondheim said of the former.

He also revealed that (at age 90, Colbert points out), he's still writing. Sondheim has been working on a new musical for the past couple of years with playwright David Ives, titled Square One. He mentions that they just held a reading of it last week, "and we were encouraged," so they will continue. It should also be noted that Nathan Lane, on his Today appearance yesterday, revealed that he had just done a reading of a new Sondheim musical with Bernadette Peters, so...putting it together...

Watch the video of the interview, which also includes a touching moment between the two as Colbert thanks Sondheim for "laying out the desire and the beauty for the act of creation itself," above.