The Light Ages (book review)

This review first appeared in Fortean Times magazine.

The Light Ages - a Medieval journey of discovery

Seb Falk, Penguin/Allen Lane, 2020

£10.99 paperback, 416 pages, bibliography, index

Front cover image for the purposes of criticism or review, fair dealing under the Copyright Act 1988

The myth of the "darkness of the Middle Ages" descending after the fall of Rome is dispelled in The Light Ages. Here historian, science historian and broadcaster Seb Falk demonstrates that "medieval science" is no contradiction in terms, while religion and science weren't antagonists in the medieval world. Falk illustrates this through a fascinating biography of John Westwyk, a thirteenth-century Benedictine monk based at St Albans abbey who wrote important treatises on astronomy, accidentally rediscovered in the 1950s.

The astrolabe was a flattened, portable model of the solar system made from brass discs slotted on top of each other, through which you could measure the "ascensions" of moving celestial bodies.

Functioning regardless of whether the universe was geocentric or heliocentric, astrolabes calculated how many daylight hours in each day, reckoned the dates of Easter, predicted when the heavens were moving into zodiacal "houses" whose influence may affect us, forewarned of planting seasons heralded by the appearance of certain stars visible just before dawn. Such calculations may have been a form of meditation for monks. Physicians' astrolabes chose auspicious times to administer bleedings. Previous inmates at St Albans had produced new discs to add to the astrolabe "for all altitudes.: Westwyk added a guide to these, demystifying earlier manuals and correcting their errors.

A copper-alloy astrolabe from the British Museum's collection. Dating from 1326, this example is believed to be the earliest surviving one made in England. It was on show at the BM's recent Thomas Beckett exhibition. Photo: Matt Salusbury

Astrolabes dominate The Light Age, and while the astrolabe was a "simplified" instrument compared to its predecessors, after a 39-page digression on astrolabes I was struggling with the azimuth and the obliquity of the elliptic. Aaargh!

This was an exciting time for astronomy. A standardised 24-hour day with 60-minute hours was proliferating, along with clocks. The long transition to Arabic numerals was apace. There was a flood of philosophical works emerging in Arabic, Greek and Hebrew - pagan sciences could now become "the handmaiden of religion".

My favourite section of The Light Age describes the rise of the universities. In 1336 the Pope called on monastic orders to send one in 20 monks to university. Today's Worcester College, Oxford began life as a Benedictine institution. As a graduate returning to the monastery, Westwyks' privileges included being excused midday Mass. The new universities were particularly awestruck by the recent rediscovery of Aristotle, his works quickly dominated the curriculum. Periodic ecclesiastical bans on the study of Aristotle were largely ignored.

Around 1370 Westwyk left for the bleak cliff-top subsidiary monastery at Tynemouth, taking with him some astronomy works to copy. Tynemouth was three degrees further north than Classical philosophers had ever been, so Westwyk wrote a treatise with instructions on engraving an astrolabe dial for "ascensions" at a new latitude, 55 degrees North.

Like many clerics, Westwyk joined the debacle that was the 1382 Bishop's Crusade (better known as Despenser's Crusade after Henry de Despenser, Bishop of Norwich). This Crusade fought not in the Holy Land, but in Belgium. Led by an incompetent warrior Bishop of Norwich, the crusaders -n outnumbered by Franco-Flemish forces loyal to anti-pope Clement - fought with extraordinary courage, the clerics in particular. They withdrew to England in disgrace within six months. Westwyk kept his head down for the next decade.

Westwyk next pops up at London's Benedictine inn, where he wrote a manual - in English, daring and innovative at the time - with instructions for building an enormous astrolabe six feet in diameter. This manual, Equatorie, is a computer and equation solver. Its 140 pages of tables allow the user to calculate the motion of the planets back to the birth of Christ and to any point in the future, adjusting for leap years, aided by charts for roots and "sexagesimal ninths". Nothing equalled the Equatorie until the first printed astronomy textbooks appeared nearly a century later.

An astrolabe of 1221 vintage, inscribed with Arabic letters, in London's Science Museum.

VERDICT: Joyous celebration of Medieval science - although a bit astrolabe-heavy! **** (four stars)

© Matt Salusbury 2021