David I. Masson] began publishing sf with Traveller's Rest for NEW WORLDS in 1965; his fiction, including this extraordinarily intense study in the distortion of PERCEPTION, was assembled in _The Caltraps of Time_ (coll 1968), which single volume established his strong reputation as a writer of vigorously experimental, vivid, often scientifically sound stories. Notable among them, and reflecting his close and informed interest in LINGUISTICS, were Not so Certain (1967) and the brilliant TIME-TRAVEL story A Two-Timer (1966), told entirely in language appropriate to 1683, the year from which the inadvertent time traveller is whisked into the future. Each of DIM's stories seems to be a solution to some cognitive or creative problem or challenge ... (John Clute, _The Encyclopedia of Science Fiction_)