New Museum presents “Bedtime Stories,” a project initiated by the artist Maurizio Cattelan. Inviting friends and other artists and performers he admires to keep us company, Cattelan imagined “Bedtime Stories” as a way of staying together during these days of isolation. Some chose to read existing works, others to read their own writings, still others to create impromptu performances. Whether drawn from memory, imagination, or cherished volumes kept close at hand, the recordings by artists were captured quickly in an unfiltered fashion on phones or laptops in their homes or studios around the world.