This webpage belongs to www.janzuidhoek.com, which is a website promoting [Jan Zuidhoek (2019) Reconstructing Metonic 19-year Lunar Cycles (on the basis of NASA’s Six Millennium Catalog of Phases of the Moon): Zwolle], and concerns this pioneering book, which is available via this website, and its author Jan Zuidhoek.
Book and Author
This book explains, by following the mainstream of the history of the computus paschalis developed from early in the third century for the purpose of determining (Alexandrian or Julian calendar) dates of Paschal Sunday which rised shortly
after AD 250 in Alexandria
(Egypt) to ultimately (in AD 1582) flow
into the modern way of determining (Gregorian calendar) dates of Easter, how of old dates of Paschal Sunday depend on phases
of the moon and, on the
basis of NASA’s Six
Millennium Catalog of Phases
of the Moon, how both lost Metonic 19‑year lunar cycles constructed
in Alexandria before the first council of Nicaea (in AD 325) can be reconstructed.
The author of this
pioneering book was born in 1938, studied mathematics, physics, and astronomy at the university of
Utrecht from 1960 to 1969, and was a teacher of mathematics from 1970 to 2001 at the
Gymnasium Celeanum in Zwolle. After
having gone deeply into the fields of history of mathematics, of chronology, and
of early Christianity, ultimately resulting in his lucid webpage “Christian Era and Universal Time”,
he became fascinated by the Alexandrian computus. In 2009 he determined the initial year (AD 271) of De ratione paschali, i.e. the medieval Latin text containing
the legendary 19‑year Paschal
cycle of the famous third century Alexandrian
computist Anatolius who invented the first Metonic 19‑year lunar cycle. The presentations he gave at the
international conferences on the science
of computus at the university
of Galway in 2010 and 2018 resulted
in 2017 in an article entitled “The initial year of De ratione paschali and the relevance of its paschal dates” and in 2019 in the first
edition of this book reducing that
article to a preparatory study.
© Jan
Zuidhoek 2019-2021