Editing Theta (section)

==Symbolism==
[[File:Retiarius vs secutor from Borghese mosaic.jpg|thumb|300px|upright|θ (θάνατος, death) in a mosaic]]
In ancient times, [[Tau]] was used as a symbol for [[life]] or [[resurrection]], whereas the eighth letter of the Greek alphabet (ninth in the archaic form anciently used for numeration), theta, was considered the symbol of [[death]].<ref name="Mednik">{{cite journal |last=Mednikarova  |first=Iveta |title=The Use of Θ in Latin Funerary Inscriptions |journal=[[Zeitschrift für Papyrologie und Epigraphik]] |volume=136 |date=2001 |pages=267–276 |jstor=20190914 }}</ref> A quotation attributed to the ancient Roman author [[Ennius]] (though possibly spuriously) said of it: "oh, theta, a letter much unluckier than the others".<ref>{{cite book |last1=Ennius |first1=Quintus |author1-link=Ennius |editor1-last=Goldberg |editor1-first=Sander M. |editor2-last=Manuwald |editor2-first=Gesine |editor2-link=Gesine Manuwald |title=Fragmentary Republican Latin, Volume I: Ennius, Testimonia. Epic Fragments. |date=2018 |publisher=Harvard University Press |location=Cambridge, MA |pages=456–457}}</ref>

According to [[Porphyry of Tyros]], the [[Ancient Egypt|Egyptian]]s used an X within a circle as a [[symbol]] of the soul; having a value of nine, it was used as a symbol for [[Ennead]]. [[Johannes Lydus]] says that the [[Egyptians]] used a symbol for [[cosmos|Kosmos]] in the form of theta, with a fiery circle representing the world, and a snake spanning the middle representing ''[[Agathos Daimon]]'' (literally: ''good spirit'').<ref name="Barry_1">{{Citation| last = Barry
| first = Kieren
| title = The Greek Qabalah: Alphabetic Mysticism and Numerology in the Ancient World
| publisher = [[Samuel Weiser]]
| page = 73
| year = 1998
| isbn=1-57863-110-6
}}.</ref>

===Abbreviation===
{{main|Theta nigrum}}
In classical Athens, it was used as an abbreviation for the [[Greek language|Greek]] θάνατος (''Thanatos'', "death") and as it vaguely resembles a human skull,<ref name="Barry_1"/> theta was used as a warning symbol of [[Thanatos|death]], in the same way that [[skull and crossbones (poison)|skull and crossbones]] are used in modern times.<ref name="Barry_1"/> It survives on [[potsherd]]s used by Athenians when voting for the [[death penalty]].<ref name="Barry_1"/> [[Petrus de Dacia (mathematician)|Petrus de Dacia]] in a document from 1291 relates the idea that theta was used to brand criminals as empty ciphers, and the branding rod was affixed to the crossbar spanning the circle.<ref>{{Citation
| last = Kaplan
| first = Robert
| title = The Nothing that Is: A Natural History of Zero
| publisher = [[Oxford University Press]]
| year = 2000
| pages = 66
| isbn = 0-19-514237-3
| bibcode = 2000tnti.book.....K
| location = Oxford; New York
}}.</ref> For this reason, the use of the number 9 was sometimes avoided where the connotation was felt to be unlucky—the mint marks of some Late Imperial Roman coins famously have the sum ΔΕ or ΕΔ (delta and epsilon, that is 4 and 5) substituted as a [[euphemism]] where a Θ (9) would otherwise be expected.