Lester del Ray: ...And It Comes Out Here: There is one fact no sane man can quarrel with ... everything has a beginning and an end. But some men aren't sane; thus it isn't always so!

This is an excellent time travelling story, with the usual logical paradoxes. This includes a trip to a museum of the future where they speak a version of English that is almost unrecognizable at times. It’s occasionally very funny and full of brilliant hard SF technical terms like the “whatdewmacallit” effect. A fascinating vision of the future earth.