In the late fifth or early sixth century, a Christian writer, most likely a monk, probably from the Syrian region of the eastern Roman Empire, composed a body of works in which the philosophy of Plotinus, Proclus and other thinkers in the Platonic tradition is united with Christian belief. The works appeared under the name of Dionysius the Areopagite, and in them the author apparently identifies himself as this first-century figure, who is named in the Acts of the Apostles as an Athenian converted to Christianity after hearing St Paul’s sermon on ‘the unknown God’ (Acts 17.34) and who is said to have become the first bishop of Athens. The author is now generally referred to as ‘Pseudo-Dionysius’, or, in order to avoid the pejorative connotations of the prefix ‘pseudo-’, simply as ‘Dionysius’ or ‘Denys’. Attempts have been made to discover his true identity, but none has received general acceptance, and in the absence of any solid evidence such efforts necessarily remain merely speculative and inconclusive. What seems clear, however, is that the author’s concealment of his own name is related to the philosophical content of his works. Like the God of whom he writes, the author remains nameless, inaccessible, hidden behind his works and knowable only as he is manifest in them. His choice of pseudonym, moreover, links him both with the idea of ‘the unknown God’ and with the integration between Greek philosophy and Christianity which is at play in Paul’s sermon.