Post tenebras lux is a Latin phrase translated as Light After Darkness.
It is Post tenebras spero lucem ("After darkness, I hope for light") in the Vulgate

Vulgate

The Vulgate is a late 4th-century Latin translation of the Bible. It was largely the work of St. Jerome, who was commissioned by Pope Damasus I in 382 to make a revision of the old Latin translations...

 version of Job

Book of Job

The Book of Job , commonly referred to simply as Job, is one of the books of the Hebrew Bible. It relates the story of Job, his trials at the hands of Satan, his discussions with friends on the origins and nature of his suffering, his challenge to God, and finally a response from God. The book is a...

 17:12
11 dies mei transierunt cogitationes meae dissipatae sunt torquentes cor meum

12 noctem verterunt in diem et rursum post tenebras spero lucem

13 si sustinuero infernus domus mea est in tenebris stravi lectulum meum.

The phrase was adopted as the Calvinist

Calvinism

Calvinism is a Protestant theological system and an approach to the Christian life...

 motto, and was subsequently adopted as the motto of the entire Protestant Reformation

Protestant Reformation

The Protestant Reformation was a 16th-century split within Western Christianity initiated by Martin Luther, John Calvin and other early Protestants. The efforts of the self-described "reformers", who objected to the doctrines, rituals and ecclesiastical structure of the Roman Catholic Church, led...

, and also of John Calvin

John Calvin

John Calvin was an influential French theologian and pastor during the Protestant Reformation. He was a principal figure in the development of the system of Christian theology later called Calvinism. Originally trained as a humanist lawyer, he broke from the Roman Catholic Church around 1530...

's adopted city of Geneva

Geneva

Geneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...

, Switzerland

Switzerland

Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

. As a mark of its role in the Calvinist movement, the motto is engraved on the Reformation Wall

Reformation Wall

The International Monument to the Reformation , usually known as the Reformation Wall, is a monument in Geneva, Switzerland...

, in Geneva, and the Huguenot Monument

Huguenot Monument

The Huguenot Monument in Franschhoek, South Africa, is dedicated to the cultural influences that Huguenots have brought to the Cape Colony after their immigration during the 17th and 18th centuries....

, in Franschhoek, South Africa

South Africa

The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

.

Post tenebras lux was formerly the state motto of Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, before being replaced by the Spanish

Spanish language

Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

 Por la razón o la fuerza ('By reason or by force'). It is the motto of American International College in Springfield, Massachusetts and is one of the two motto

Motto

A motto is a phrase meant to formally summarize the general motivation or intention of a social group or organization. A motto may be in any language, but Latin is the most used. The local language is usual in the mottoes of governments...

s of Robert College

Robert College

Robert College of Istanbul , is one of the most selective independent private high schools in Turkey. Robert College is a co-educational, boarding school with a wooded campus on the European side of Istanbul between the two bridges on the Bosphorus, with the Arnavutköy district to the east, and...

, an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 school in Istanbul

Istanbul

Istanbul , historically known as Byzantium and Constantinople , is the largest city of Turkey. Istanbul metropolitan province had 13.26 million people living in it as of December, 2010, which is 18% of Turkey's population and the 3rd largest metropolitan area in Europe after London and...

, Turkey

Turkey

Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

 and also the motto of Beyoglu Anadolu Lisesi in Istanbul (former English High School For Girls). It is also the motto of Externado de Colombia University

Universidad Externado de Colombia

The Universidad Externado de Colombia in Bogotá, Colombia, is a private university which grants 4 and 5 year primary and professional degrees as well as advanced 2-year Magister degrees. Instruction is primarily in Spanish. The dean is Dr...

.