Ad fontes is a Latin expression which means "to the sources" (lit. "to the fountains"). The phrase epitomizes the renewed study of Greek

Greek literature

Greek literature refers to writings composed in areas of Greek influence, typically though not necessarily in one of the Greek dialects, throughout the whole period in which the Greek-speaking people have existed.-Ancient Greek literature :...

 and Latin

Latin literature

Latin literature includes the essays, histories, poems, plays, and other writings of the ancient Romans. In many ways, it seems to be a continuation of Greek literature, using many of the same forms...

 classics in Renaissance humanism

Renaissance humanism

Renaissance humanism was an activity of cultural and educational reform engaged by scholars, writers, and civic leaders who are today known as Renaissance humanists. It developed during the fourteenth and the beginning of the fifteenth centuries, and was a response to the challenge of Mediæval...

. Similarly, the 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...

 called for renewed attention to the Bible

Bible

The Bible refers to any one of the collections of the primary religious texts of Judaism and Christianity. There is no common version of the Bible, as the individual books , their contents and their order vary among denominations...

 as the primary source of Christian

Christianity

Christianity is a monotheistic religion based on the life and teachings of Jesus as presented in canonical gospels and other New Testament writings...

 faith. The idea in both cases was that sound knowledge depends on the earliest and most fundamental sources.

This phrase is related to Ab initio

Ab initio

ab initio is a Latin term used in English, meaning from the beginning.ab initio may also refer to:* Ab Initio , a leading ETL Tool Software Company in the field of Data Warehousing.* ab initio quantum chemistry methods...

, which means "from the beginning." Whereas ab initio implies a flow of thought from first principles

First principles

In philosophy, a first principle is a basic, foundational proposition or assumption that cannot be deduced from any other proposition or assumption. In mathematics, first principles are referred to as axioms or postulates...

 to the situation at hand, ad fontes is a retrogression, a movement back towards an origin, which ideally would be clearer than the present situation.

The phrase ad fontes occurs in the Latin Vulgate version of Psalm 42

Psalm 42

Psalm 42 op. 42 "Wie der Hirsch schreit" is a composition by Felix Mendelssohn composed in 1837/38 for soloists, mixed choir and orchestra....

:

quemadmodum desiderat cervus ad fontes aquarum ita desiderat anima mea ad te Deus.

According to Hans-Georg Gadamer

Hans-Georg Gadamer

Hans-Georg Gadamer was a German philosopher of the continental tradition, best known for his 1960 magnum opus, Truth and Method .-Life:...

, there is evidence provided by E. Lledo that Spanish humanists drew the expression from this source.

Erasmus of Rotterdam

Desiderius Erasmus

Desiderius Erasmus Roterodamus , known as Erasmus of Rotterdam, was a Dutch Renaissance humanist, Catholic priest, and a theologian....

used the phrase in his De ratione studii ac legendi interpretandique auctores:

Sed in primis ad fontes ipsos properandum, id est graecos et antiquos.