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Sator square

A Sator Square (laid out in the SATOR-format), etched onto a wall in the medieval fortress town of Oppède-le-Vieux, France

Sator Square is a wide expanse of cobbles outside the black gates of the University. It is a central meeting point and marketplace (Saturdays) in Ankh-Morpork, a wide-open public space with fountains, upon one side of which are the Great Gates of Unseen University. It is overlooked by the Clock Tower (housing Old Tom) and connected to Plaza of Broken Moons by the Cham.

In Soul Music, the Band with Rocks In are told to report here, to the offices of their new manager C.M.O.T. Dibbler. It takes them some time to realise that Dibbler has a very open-plan office, from which he usually sells sausage-inna-bun from a tray slung round his neck...

In Sourcery, the recently empowered wizards descend on Sator Square and clear it of all the traders and stalls. Miskin Koble sells jellied starfish and clams until he confronts one of the wizards for destroying his stall, at which point he is eliminated with nothing but his smoking boots remaining. Ardrothy Longstaff, Purveyor of Pies with Personality also has a stall there until it too is destroyed by the wizards urban renewal efforts.

Sator Square is also a place where free speech is allowed, if not encouraged, and is a place for ranters, haranguers, and self-absorbed mumblers to say their piece. This all comes under the heading of street theatre, and no doubt the Patrician has somebody in the crowd to memorise names and faces and take notes, on the off-chance that what is said might actually be important, or lead to consequences.


Pratchett's Sator Square is a clever word play on the famous magic square dating back to the times of the spread of Christianity in Europe. 'Sator' means sower or farmer. The complete square is palindromic in all directions. It is also the oldest double acrostic. The magic square appears throughout Europe, Asia Minor and North Africa on walls, in books and manuscripts It is considered to be the closest thing to a meme of the era. It even appears in several early and late medieval medical textbooks such as the Trotula, and was employed as a medieval cure for many ailments, particularly for dog bites and rabies, as well as for insanity, and for relief during childbirth - continuing even into the 19th century in North and South America. The earliest one dates from pre-62 BC in Pompeii Italy. The words of the square when laid out as a sentence read: Sator Arepo Tenet Opera Rotas. Some of the various interpretations are given below.

The magic Sator square also has the property that it can be 'unfolded' into two "A PATER NOSTER O" strings that form a cross with the 'N' as a pivot element The 'A' and the 'O' stand for the 'alpha' and 'omega', the beginning and end in the Greek alphabet and the title of God in the Book of Revelations.

The individual words are in Latin and translate as follows:

SATOR - nominative or vocative noun; from serere, 'to sow') sower, planter, founder, progenitor (usually divine); originator; literally 'seeder'.

AREPO - unknown word, potentially a proper name, either invented to complete the palindrome or of a non-Latin origin (see "Arepo interpretations" below).

TENET - (verb; from tenere, 'to hold') he/she/it holds, keeps, comprehends, possesses, masters, preserves, sustains.

OPERA - (nominative, accusative or vocative [see opus] plural noun) work, care, aid, labour, service, effort/trouble; (from opus): (nominative, accusative or vocative noun) works, deeds; (ablative) with effort.

ROTAS - (rotās, accusative plural of rota) wheels; (verb) you (singular) turn or cause to rotate

The most direct sentence translation is: "The sower (or, farmer) Arepo holds the wheels with care (or, with care the wheels)". Similar translations include: "The farmer Arepo works his wheels", or "Arepo the sower (sator) guides (tenet) the wheel (rotas) with skill (opera)".

Some academics, such as French historian Jules Quicherat, believe the square should be read in a boustrophedon style (i.e. in alternating directions). The boustrophedon style, which in Greek means "as the Ox plows", emphasizes the agricultural aspect of the square. Such a reading when applied to the SATOR-form square, and repeating the central word TENET, gives SATOR OPERA TENET – TENET OPERA SATOR, which has been very loosely interpreted as: "as ye sow, so shall ye reap", while some believe that the square should be read as just three words – SATOR OPERA TENET, which has been very loosely translated as: "The Creator, the author of all things, maintains his works"; both of which could imply Graeco-Roman Stoic and/or Pythagorean origins.

British academic Duncan Fishwick observes that the translation from the boustrophedon approach fails when applied to a ROTAS-form square, however, Belgian scholar Paul Grosjean reversed the boustrophedon rule on the ROTAS-form (i.e. starting on the right-hand side instead of the left) to get SAT ORARE POTEN, which loosely translates into the Jewish call to prayer, "are you able to pray enough?".

Arepo interpretations[]

The word AREPO is a hapax legomenon (i.e. it appears nowhere else in Latin literature). Some academics believe it is likely a proper name or potentially a theophoric name, that was adapted from a non-Latin word or was invented specifically for the Sator square. French historian Jerome Carcopino interpreted AREPO as the Greek ἅπαξ, and believed that it came from the Gaulish word for a 'plough'; this has been discounted by other academics. American ancient legal historian David Daube believed that AREPO represented a Hebrew or Aramaic rendition of the ancient Greek for alpha (Ἄλφα) and omega (ω), giving the "Alpha-Omega" concept (cf. Isiah 44.6, and Revelation 1:8) from early Judeo-Christianity. J. Gwyn Griffiths contended that the term AREPO came, via Alexandria, from the attested Egyptian name "Hr-Hp" (ḥr ḥp), which he took to mean "the face of Apis". In 1983, Serbian-American scholar Miroslav Marcovich proposed the term AREPO as a Latinized abbreviation of Harpocrates (or "Horus-the-child"), god of the rising sun, also called Γεωργός `Aρπον, which Marcovich suggests corresponds to SATOR AREPO. This would translate the square as: "The sower Horus/Harpocrates checks, toils, and tortures".

Duncan Fishwick, amongst other academics, believed that AREPO was simply a residual word that was required to complete what is a complex and sophisticated palindrome which Fishwick believed was embedded with hidden Jewish symbolism and to expect more from the word was unreasonable from its likely Jewish creators.

Paternoster theory[]

Our Father anagram of the square

Lord's Prayer anagram from the 25 letters of the square, including the Alpha and Omega positioning of the residual As and Os. There is an alternate layout proposed with the As and Os positioned at the extreme ends of the Paternoster cross, and a Jewish option with the letters laid out in an X-shape (i.e. tau).

During 1924–1926, three people separately discovered, or rediscovered, that the square could be used to write the name of the Lord's Prayer, the "Paternoster", twice and intersecting in a cross-form (see image opposite). The remaining residual letters (two As and two Os) could be placed in the four quadrants of the cross and would represent the Alpha and Omega that are established in Christian symbolism. The positioning of the As and Os was further supported by the fact that the position of the Ts in the Sator square formed the points of a cross – there are obscure references in the Epistle of Barnabas to T being a symbol of the cross – and that the As and Os also lay in the four quadrants of this cross. At the time of this discovery, the earliest known Sator square was from the fourth century, further supporting the dating of the Christian symbolism inherent in the Paternoster theory. Academics considered the Christian origins of the square to be largely resolved.

With the subsequent discovery of Sator squares at Pompeii, dating pre-79 A.D, the Paternoster theory began to lose support, even amongst notable supporters such as French historian Guillaume de Jerphanion. Jerphanion noted: that (1) it was improbable that many Christians were present at Pompeii, that (2) first century-Christians would have written the square in Greek and not Latin, that (3) the Christian concepts of Alpha and Omega only appear after the first century, that (4) the symbol of the cross only appears from about A.D 130–131, and that (5) cryptic Christian symbols only appeared during the persecutions of the third century.

Jérôme Carcopino claimed the Pompeii squares were added at a later date by looters, however, the lack of any disturbance to the volcanic deposits at the palestra meant that this was unlikely, and the Paternoster theory as a proof of Christian origination lost much of its academic support.

Regardless of its Christian origins, many academics considered the Paternoster discovery as being a random occurrence to be mathematically impossible. Several examined this mathematical probability including German historian Friedrich Focke [de] and British historian Hugh Last, but without reaching a conclusion. A 1987 computer analysis by William Baines derived a number of "pseudo-Christian formulae" from the square but Bains concluded it proved nothing.