Cathedrale Notre-Dame de Chartres, located in Chartres, France. Chartres is considered one of the finest examples of the French High Gothic style. The current cathedral, mostly constructed between 1193 and 1250, is one of at least five structures that have occupied the site since  the 4th century.

Labyrinth at Chartres


Labyrinth designs appear on pottery, baskets, on wall of caves, and in churches. Many labyrinths set in floors or on the ground are large enough that the path to the center and back can be walked. Historically labyrinths have  been used both in group ritual and for private meditation. One of the most famous labyrinths is on the floor of Chartres cathedral. The original function of the Chartres labyrinth is still debated, but the evidence does indicate, at least, a tentative conclusion.


The labyrinth at Chartres Cathedral. Early 13th century. Approximately 42 feet across.



There are 112 cusps around the outer circle (see below), and four sections or quarters in the design. If you divide 112 by 4, the answer is 28, the days of a lunar month. This led to the belief that the labyrinth originally served as a calendar. If so, the four sections represent the four season and  provided a means of keeping track of the lunar cycles of 28 days between new moons. With such a calendar the church could determine the very important  date of  Easter and other movable feast days.

The First Council of Nicaea (325) established the date of Easter as the first Sunday after the full moon (the Paschal Full Moon) following the northern hemisphere's  vernal equinox. Ecclesiastically, the equinox is reckoned to be on March 21 (even though the equinox occurs, astronomically speaking, on March 20 in most years), and the "Full Moon" is not necessarily the astronomically correct date. The date of Easter therefore varies between March 22 and April 25. Eastern Christianity bases its calculations on the Julian Calendar whose March 21 corresponds, during the 21st century, to the 3rd of April in the Gregorian Calendar, in which calendar their celebration of Easter therefore varies between April 4 and May 8.

There are  actually 29.5306 days  between consecutive new moons, not 28, and the mediaeval scholars and clerics were well aware of this awkward number.  They created complex lunar calendrical systems with alternating months of 29 and 30 days, with additional intercalated months and inserted leap days, to keep the theoretical lunar cycle in sequence with the solar calendar.  This system was devised  by Dionysius Exiguus,* a Sythian monk, during the early 6th century AD. His tables  determine in advance the date of the first full moon that would occur on or after the spring equinox in any given year, and thus calculate the date of Easter, the primary festival of the Christian Church.

There are 112 cusps around the halo of the labyrinth.


In medieval Christian manuscripts  these tables were sometimes accompanied by drawings of labyrinths, presumably to illustrate the complexity of the subject matter. This juxtaposition may have been influential in the subsequent connection between labyrinths and Easter festivals and ritual dances in the cathedrals of Italy and France. The complex alternating circuits of the labyrinth were taken as symbolic of the intermeshing cycles of the calendars, as well as the spheres on which the sun, moon and planets moved around the firmament against the background of the fixed stars. Beyond these circuits lay additional spheres representing the spiritual heavens, where saints and angels resided. The use of labyrinths to exemplify this order demonstrates  the complex relationship  of the scientific and spiritual worlds of medieval thought.


Aristotle Ptolemaic Cosmos.


Medieval man believed humans consisted of four elements, earth, water, air, and fire, which determined personality. The right balance of these humors was necessary, to prevent one from being overtaken by passions. Also they believed that the stars affected the balance between the humors. Thus, born under an evil star and you were cursed.

Another important belief in the medieval world view was that everything was arranged in hierarchies. The king was at the top of the political order and the pope at the top of the religious order, on down to the farmers at the bottom. Maintaining the hierarchies preserved the world order and its relationship with the heavenly order. Therefore everyone in society had to perform their role and cooperate in order to make the society function smoothly. Life on earth had to be in balance with the heavenly order; this order began anew at Easter.

Church officials at Chartres could located Easter on the labyrinth, then mark other dates of the church calendar: for example, Ash Wednesday (46 days before Easter) and Pentecost (49 days after Easter). So anyone around Chartres could check this public calendar at the cathedral and prepare for a particular feast day, just as today we check our  personal  desk calendars for holidays.  Religious rituals maintained the cultural order, keeping the relationship between earth and heaven properly functioning throughout Christendom.

Their Goecentric or Ptolemaic model held that the Earth is the center of the universe, and that all other objects orbit around it. This geocentric model served as the predominant cosmological system in the west beginning with the ancient Greeks. Two commonly made observations supported the idea that the Earth was the center of the Universe.

1) The stars, sun, and planets appear to revolve around the Earth each day, making the Earth the center of that system. Stars are on a celestial sphere that rotated each day, using a line through the north and South pole as an axis.

2) The second common sense notion supporting the geocentric model was that the Earth does not seem to move from the perspective of an observer on Earth. Aristotle, assuming a reasonable universe, said the Earth did not move because it had no reason to move.

This geocentric system was challenged by Galileo's championing of Heliocentrism. He met with opposition from astronomers, who doubted Heliocentrism due to the absence of an observed stellar parallax. The matter was investigated by the Roman Inquisition in 1615, and they concluded Heliocentrism could only be supported as a possibility, not as an established fact.

Pope Urban VIII, a personal supporter of Galileo, asked him to give arguments for and against Heliocentrism in his next book, and to be careful not to advocate Heliocentrism. He made another request, that his own views on the matter be included in Galileo's book. Only the latter of those requests was fulfilled by Galileo. Whether unknowingly or deliberately, Simplicio, the defender of the Aristotelian Geocentric view in Dialogue Concerning the Two Chief World Systems, came across as a fool. The name "Simplicio" in Italian  has the connotation of simpleton. Galileo put the words of Urban VIII into the mouth of Simplicio.  The Pope was outraged. Galileo had alienated his biggest and most powerful supporter.  Now Galileo was forced to face the Jesuits and the Inquisition alone. He was tried by the Inquisition, forced to recant, and spent the rest of his life under house arrest. All books on Heliocentrism were banned.

Part of the reason the Roman church officials opposed Galileo's system was their correctly perceived threat to the established medieval system outlined above.** The human drama of an ordered alignment of earth with heaven would eventually be replaced with a scientific yet meaningless universe of black holes and dark matter we live in today. Put another way, Thomas Aquinas and his world of system and order was replaced by Hamlet and his disconnected world of doubt and uncertainty.

 Note: The Inquisition's ban on Galileo's works was lifted in 1718, except for the condemned Dialogue. In 1758 the general prohibition against works advocating Heliocentrism was removed from the Index of Prohibited Books, although the ban on uncensored versions of the Dialogue and Copernicus's De Revolutionibus remained in effect. Finally, all official opposition to Heliocentrism by the church was dropped in 1835 when these works were removed from the Index.

* Dionysius was the first known medieval Latin writer to use a precursor of the number zero.  The Latin word non or nulla meaning no/none was used because there was  no Roman number for zero.

** The Jesuits objected to Galileo's contention that the moon is a flawed object. Heavenly bodies were taken to be perfect, i.e. "heavenly". Galileo wrote, if the moon is in a heavenly sphere and its light shines on the pales of my garden fence, does that not make my fence heavenly? Placing earth in a heavenly sphere and bringing heaven down to earth upset the medieval cosmos; not to mention the Jesuits. The best piece covering this topic is "Moon Man" by Adam Gopnik that appeared in the  New Yorker.