Sir, - Brian Boyd (Millennium Mystique, February 20th) repeats some half-truths about Dionysius Exiguus which require correction. It was not Dionysius but the Venerable Bede (673-735) who introduced the idea of BC dates. Bede had only Roman numerals so the AD/BC system lacks a Year Zero and the origin of our calendar is the instant 00hrs on January 1st, AD1. Adding 2,000 gives January 2001 as the start of the Third Millennium.
Dionysius overlooked six years in his calculations: four when Emperor Augustus reigned under his family name of Octavian and two when Tiberius ruled in Syria before succeeding Augustus. This moves Christ's notional birth date of December 25th from 1BC to 7BC and implies that the 2000th anniversary of his birth should have been celebrated on December 25th, 1994.
Boyd's "big round number" of 2000 contains three zeros. It is not generally realised that the marvellous invention of zero was made in India by Hindu mathematicians about the sixth century AD and that so-called Arabic numerals reached Western Europe only about 1500. - Yours, etc., Dr Ian Elliott,
Pinecroft, Kilternan, Dublin 18.