History of this Holy Hymn
St. Nectarios was a Bishop of the Greek Orthodox Church throughout the late 1800s, and early 1900s. Throughout the period of his episcopacy, he spent much time in prayer and contemplation, and dedicated himself to the monastic life. His spiritual lifestyle, and his particular dedication to the Virgin Mary inspired him to write a wide variety of religious poetry, much of which was published during his life, and after his repose in 1920.
One of the many poems he wrote is "Agni Parthene" or "O Virgin Pure". According to a tradition passed down on the island of Aegina, St. Nectarios reportedly composed the text for this poem after having seen a vision of the Theotokos in a dream where she asked him to record this poem. The original script can still be viewed on his prayer table in his bedroom at this monastery.
It was later published as a poetic hymn for non-liturgical use and private edification in his publication called "Theotokarion of Odes & Hymns for the Most-Holy Theotokos and Ever-Virgin Mary" of 1905, which included many other similar poems