Medieval Time: The Numbering of Days

One of the gripes I have with writing fiction set in the Middle Ages is having to dispense with modern conveniences.

Take washing machines, for example. You don’t get many books from the olden days with a washerwoman as a heroine. Why? Because she didn’t have time to do anything but laundry. If she’d had a Whirlpool FSCR10432, she might have had time for romantic intrigues and coach-rides with dukes. As it was, she was too busy getting up close and personal with tunic-grime.

The same goes for mechanical clocks.  Imagine my disgust when I realized that two of my characters would have to make an appointment to meet the following day! I couldn’t have the friar say, “I’ll phone you at seven o’clock in the morning.” The best I could do was, “Meet me by the gate at sunrise,” not very fair on the Saracen boy who’d have to get up so early and hang around picking his teeth (though, if you think about it, life probably wouldn’t have been fair for a Saracen boy in fourteenth-century Italy).

In view of my troubles, I was glad to see that there was an exhibition going on at the Morgan Library and Museum in New York with the theme ‘Time in the Middle Ages’.  I hopped on the R train to Manhattan and looked forward to getting some answers.

Disappointingly, the sign at the portal warned me that I wouldn’t be seeing any clocks. Possibly as a sop to those of us who wanted them, the sign appeared underneath this illuminated personification of Temperance  balancing a clock on her head and holding a horse’s bridle between her teeth.


Temperance. Book of Hours France, Paris, 1430-1435 MS M.359 fol. 117v

Instead of practical time-keeping devices like clocks, the sign explained, I would be seeing documents and objects that showed how Medieval Europeans thought about time. This seemed a bit abstract, but it was better than nothing.


Chronicles — the Overview, from Creation to the Apocalypse

The first thing I saw when entering the exhibition room was a big glass case containing a couple of wide scrolls, each unrolled to reveal a small section. La Cronique Anonyme Universelle, for example, was an illustrated chronology of time from Creation to the fifteenth century. The main points of significance were events mentioned in the Bible, highlights of Classical literature (such as the Fall of Troy in the circle on the right), and royal genealogies (the coronation depicted on the left shows King David, a Biblical figure who often represented the ideal king).

A tiny section of La Chronique Anonyme Universelle, Northern France, 1473–83, The Morgan Library & Museum, MS M.1157

Moving to the right, I was intrigued to see a lot of illuminated manuscripts depicting the ‘seven headed beast of the Apocalypse’ and ‘the woman of the Apocalypse’ (“A woman clothed with the sun, and the moon under her feet, and upon her head a crown of twelve stars” (12:1) Book of Revelation Ch. 12) and just plain Hell.

False Prophet directs Worship of Beast
False prophet who directs the beast of the Apocalypse. France, probably Lorraine 1290-1299.
Mouth of Hell from The Hours of Catherine of Cleves (Utrecht, 1440)


All this emphasized that life in the body was short and the life of the soul (and damnation) was eternal; a human’s life on earth only mattered in terms of the spiritual harvest, post mortem. A prayer by the Venerable Bede (c.672-735) shows that time and death are earthly conditions, that heaven is eternal, literally ‘outside of time’:

Christ is the morning star who when the night of this world is past brings to his saints the promise of the light of life and opens everlasting day. 


Parliament and Limbo
Parliament of Heaven and a Rare Depiction of Limbo, Book of Hours, Northeastern France or Paris, ca. 1465, illuminated by the Master of Jacques de Luxembourg, The Morgan Library & Museum, MS M. 1207, purchased on a grant provided by the Bernard H. Breslauer Foundation and with a gift from Marguerite Steed Hoffman, member of the Visiting Committee to the Dept. of Medieval and Renaissance Manuscripts, 2017. Image courtesy of Dr. Jörn Günther, Rare Books AG.



San Zeno Astrolabe, Italy, Verona, ca. 1455, illuminated for the Abbey of San Zeno by an anonymous Lombard artist, private collection of Michael Stone. Image courtesy of Map & Atlas Museum of La Jolla, Michael Stone, Founder

I spent about ten minutes looking at this thing in complete bafflement. It looked like the section of a giant tree covered with indecipherable scribbles and kid art. Allegedly, Benedictine monks in an abbey in San Zeno used it as ‘a rudimentary computer‘ to plan their devotional lives. This included ‘days favorable for blood-letting.’ Clearly, more information was needed.

‘Astrolabe’ is derived from the Greek word astrolabes —‘star-catcher’–and may have been invented by Hipparchus of Nicaea (c.190-120 BCE), though he was clearly influenced by Babylonian astronomical knowledge and techniques, and the design was subsequently honed and streamlined by a lot of Arab mathematicians after him. Its function was to measure the inclined position in the sky of a celestial body. It could be used to identify a star or planet, to determine local latitude given local time, to survey or to triangulate (find the position of an unknown point, e.g. Mecca, using triangles from two known points).

Exploded view of an astrolabe. The ‘mater’ is on the far left, the ‘rete’ is on the far right.

The base of an astrolabe is a big disc called the ‘mater’ (mother), deep enough to fit  one or more plates (called ‘tympanum/tympana’) inside it. The rim of the mater is often marked with hours of time or degrees of arc. Each inner plate is designed for a particular latitude and engraved with a stereographic projection of circles showing azimuth, altitude and showing the part of the celestial sphere above the local horizon. On top of this is the rete (net), a projection of the ecliptic plane (the circular path of the sun across the sky throughout the year) which usually includes pointers to some of the brightest stars. You can see a 10-minute presentation on how to use it by Tom Wujec.



Sun Dials

First of all, there were sun-dials. Here is one:

World’s oldest known sun-dial from the Valley of the Kings (1500 BCE)


Canonical Hours 

The Church day (and therefore everyone’s) was divided up into eight ‘canonical hours’–times to attend a religious service. This concept was familiar to me as I’d lived in Saudi Arabia, which observes seven communal prayer times per day (fajr, sunrise, dhur, asr, maghrib, isha, quiyam). As soon as the muzzein starts his wistful call, everyone knows what time it is, and shopkeepers start booting you out because it’s illegal to keep trading during the sacred interludes.

In Medieval Christendom, the canonical hours were named lauds, prime, terce, sext, none, vespers and compline. Incidentally, the names of the hours show their origin, the Roman system of divvying up available hours of sunlight. When the bell rang at prime (dawn, the ‘first’ hour) the men pulled their togas on and strolled to the forum. At sext (i.e. the sixth hour or noon) the lunch gong went and they toddled off for a nap. At nones (the ninth hour) a bell summoned them back to work. Jews were the first to spiritualize this system, fixing them for times of daily prayer. Christians followed suit and eventually some special significance was attached to each prayer time. For example, nones (about 3 p.m.) is traditionally the time to commemorate the death of Christ because of this heart-stopping reference to the Passion in Mark 15:34:

At the ninth hour Jesus cried with a loud voice, “Eloi, Eloi, lema sabachthani?” which is, being interpreted, My God, my God, why has thou forsaken me? (King James Bible)



Now, calendars take some explanation and I’m not sure I have it all figured out yet (I would appreciate any reading suggestions you might have). However, it’s clear that medieval European man owed most of what he knew to the Egyptians, Babylonians, Greeks, Romans, Byzantines and Arabs.

The Babylonians were the ones who invented the concept of degrees and divided the circle into 360 degrees, then divided the ecliptic into twelve equal ‘signs’ analogous to twelve schematic months of thirty days each. Each ‘sign’ contained 30 degrees of celestial longitude, creating the first known celestial coordinate system.

The Egyptians probably inherited quite a lot of this ‘Chaldean knowledge’ from the Babylonians. The Dendera Zodiac , an Egyptian star map from the Greco-Roman era, is the first known depiction of the classical zodiac of twelve signs (though many have a peculiarly Egyptian take, for example Aquarius is represented by the Hapi, god of the Nile).



The Roman calendar , particularly its Julian version, was used until 1582, the time of Gregorian reform. The Romans had a fussy system of counting backwards from three fixed points of a month ‘kalends’ (the first), ‘nones’ (7th or 5th) and the ‘ides’ (15th or 13th), and the Middle Agers saw no reason to change it. In this page from a Book of Hours, the initial KL refers to the calends, then the nones and ides are signaled with gold letters. The days marked in scarlet are so-called ‘red-letter’ days, ones with special significance for the church, usually celebrating some prominent saint. 

France (possibly Loire Valley), c. 1470.


You may notice there is a little man in the roundel doing some gardening. That’s because this is a leaf for the month of May and medieval calendars often depicted the appropriate labor for that month. Here the man is pruning branches. In the splendiferous picture below, it’s the month of September and people are harvesting ripe grapes.




Liturgical calendar for Ravenna, Italy, Milan (?), 1386, illustrated by a follower of Giovannino de’ Grassi, The Morgan Library & Museum, MS M.355, fol. 8v (detail), purchased by Pierpont Morgan, 1909.


Other Stuff

Candle clocks. The wax would burn steadily away and you could tell how much time had passed by looking at the gradation marked on or next to the candle. An early version of the alarm clock could be fashioned by sticking a nail through the wax at a certain point–when the wax melted, the nail would clatter down onto a metal plate and wake you up.

candle clock

Water Clock/Clepsydra

Clepsydra literally means ‘water-stealer’. Don’t ask me how it works, but the Greeks and Egyptians used it. Probably would not work very well in climates where water freezes.



These were handheld star-pointer thingies.




The volvelle was a moveable wheel-chart that let you work out the position of the sun and the moon in the zodiac.



So, there you have it. Time.