The frontier of the American musical theater is wherever Harold Prince and Stephen Sondheim are. Last season, the producer-director and composer-lyricist collaborated on Company, which focused a diamond-cutting laser beam on marriage, Manhattan-style. With Follies, Prince and Sondheim, together with Choreographer and Co-Director Michael Bennett, have audaciously staked out some unknown territory. They have put together the first Proustian musical….

Compacted of memory, dreams and desire, the illusions and disillusions of love, the shifting structure of the self, Follies fuses all into one of the great haunting themes of the Western mind: Time. Follies is a triple-edged title. It means the Ziegfeld Follies, the follies of people in love, and the follies one commits by not fully knowing who one is or what one wants….

The replica of a Follies show highlights the evening. The recreation is titled Loveland, and there is a shivery moment as the tall...