The Holy Spirit Dictating to Pope St. Gregory I, ivory relief panel, 10th century, Kunsthistorisches Museum, Vienna
Since, then, we have shown what manner of man the pastor ought to be, let us now set forth after what manner he should teach. For, as long before us Gregory Nazianzenus of reverend memory has taught, one and the same exhortation does not suit all, inasmuch as neither are all bound together by similarity of character. For the things that profit some often hurt others; seeing that also for the most part herbs which nourish some animals are fatal to others; and the gentle hissing that quiets horses incites whelps; and the medicine which abates one disease aggravates another; and the bread which invigorates the life of the strong kills little children. Therefore according to the quality of the hearers ought the discourse of teachers to be fashioned, so as to suit all and each for their several needs, and yet never deviate from the art of common edification. For what are the intent minds of hearers but, so to speak, a kind of tight tensions of strings in a harp, which the skillful player, that he may produce a tune not at variance with itself, strikes variously? And for this reason the strings render back a consonant modulation, that they are struck indeed with one quill, but not with one kind of stroke. Whence every teacher also, that he may edify all in the one virtue of charity, ought to touch the hearts of his hearers out of one doctrine, but not with one and the same exhortation.Today is the feast day of St. Gregory I, a former Benedictine monk who was elevated to the papacy on September 3, 590. (The day of Gregory's death, March 12, has also long been associated with him.) In the legend shown here, Gregory writes down his commentary on the Book of Ezechiel with the assistance of the Holy Spirit, perched on his shoulder in the shape of a dove. This scene was modified during the Carolingian recension of liturgical chant, showing Gregory writing chant melodies instead of text. That image was spread throughout the Carolingian empire, to enhance the authority of what came to be called the cantus Gregorianus, or Gregorian chant, long after Gregory's death.
-- Gregory the Great (c. 540-604), Liber Regulae Pastoralis (On Pastoral Rule), Prologue to Book 3
Although Gregory intended the passage quoted above to be applied to a bishop's teaching, it is good for all teachers to remember that each student in any class is a different string. Among Gregory's other important books are the Commentary on the Book of Job and the Homilies on the Book of Ezechiel, the entire Latin text of which you can also read online from the manuscript Cod. Sang. 211 in the St. Gallen Stiftsbibliothek.