John of Damascus in the context of "Canon (hymnography)"

The Guild of Saint Luke was the most common name for a city guild for painters and other artists in early modern Europe, especially in the Low Countries. They were named in honor of the Evangelist Luke, the patron saint of artists, who was identified by John of Damascus as having painted the Virgin's portrait.

One of the most famous such organizations was founded in Antwerp. It continued to function until 1795, although by then it had lost its monopoly and therefore most of its power. In most cities, including Antwerp, the local government had given the Guild the power to regulate defined types of trade within the city. Guild membership, as a master, was therefore required for an artist to take on apprentices or to sell paintings to the public. Similar rules existed in Delft, where only members could sell paintings in their city or have a shop. The early guilds in Antwerp and Bruges, setting a model that would be followed in other cities, even had their own showroom market stall from which members could sell their paintings directly to the public.

The absence of good (Latin: privatio boni), also known as the privation theory of evil, is a theological and philosophical doctrine that evil, unlike good, is insubstantial, so that thinking of it as an entity is misleading. Instead, evil is rather the absence, or lack ("privation"), of good. This also means that everything that exists is good, insofar as it exists; and is also sometimes stated as that evil ought to be regarded as nothing, or as something non-existent. Evil, on this view, is parasitic upon the good whose absence or corruption it presupposes.

The theory is most closely associated with late antique and medieval Christian thought, especially Augustine of Hippo, who adapted Neoplatonic ideas (notably from Plotinus) and argued that evil is a privation of the goodness that God has created in all things. It was further developed by figures such as Boethius, Pseudo-Dionysius, John of Damascus, and Thomas Aquinas, and later taken up—often in modified forms—by early modern philosophers like Spinoza and Leibniz.

In Christian theology, perichoresis (from Ancient Greek: περιχώρησις, romanized: perikhōrēsis, lit. 'rotation') is the relationship of the three persons of the triune God (Father, Son, and Holy Spirit) to one another. The term was first used theologically by the Church Fathers. As a noun, the word first appears in the writings of Maximus Confessor (d. 662), but the related verb perichoreo is found earlier in the work of Gregory of Nazianzus (d. 389/90). Gregory used the word to describe the relationship between the divine and human natures of Christ, as did John of Damascus (d. 749), who also extended it to the "interpenetration" of the three persons of the Trinity, and it became a technical term for the latter. "Circumincession" is a Latin-derived term for the same concept. However, the idea was present in Latin Christianity even before the Eastern fathers; this is made explicit by St. Hillary's De Trinitate. Augustine also writes in his De Trinitate (On the Trinity):

The term has been given recent currency by such contemporary writers as Jürgen Moltmann, Miroslav Volf, John Zizioulas, Richard Rohr, and others. Modern authors extend the original usage as an analogy to cover other interpersonal relationships. The term "co(-)inherence" is sometimes used as a synonym.