What Is a Canon?

Ancient Jews and Christians quoted the Bible a lot, and these quotations provide extremely helpful information regarding the development of the biblical canon. But lists of quoted books, even lists of books quoted as scripture, are not the same as canon lists.

See Also: The Biblical Canon Lists from Early Christianity: Texts and Analysis (Oxford University Press, 2019).

By Edmon L. Gallagher
Associate Professor of Christian Scripture
Heritage Christian University
August 2019

The biblical canon is an idea, a concept that exists inside someone’s head. When biblical scholars use the word “canon,” they refer to the collection of Scriptures that Jews or Christians consider have binding authority. But, of course, today there is not just one canon, but multiple; different Christian groups sometimes have different biblical canons. These differences are sometimes reflected in the physical Bibles they use, but, as we shall see, not always. As I said, the biblical canon—the identity of the authoritative books—is really an idea in someone’s head. That fact makes it a little difficult to interpret correctly the contents of someone’s biblical canon, certainly an ancient someone’s biblical canon, even when they list its contents for us. Nevertheless, despite the difficulties of interpreting biblical canon lists, they do provide our surest guide to what an ancient person considered canonical.

In this essay, I want to discuss some of the difficulties in interpreting the biblical canon lists that have been preserved for us from Late Antiquity. But first I want to clarify why I think the canon lists are important by explaining why other possible (and frequently cited) sources of information for the biblical canon can be misleading in that regard.

My contention is that we are on the safest ground in determining which books ancient people considered canonical when they explicitly tell us which books they considered canonical.

Manuscripts: Canon as a Physical Object?

Scholars studying the biblical canon have routinely discussed biblical manuscripts as important sources—whether we’re talking about the Dead Sea Scrolls or the Greek biblical pandects from the fourth century CE (Vaticanus, Sinaiticus).  I don’t dispute that these manuscripts do provide important information regarding the canon (which I will discuss later), but the basic methodological issue I want to highlight here is that manuscripts are not canon lists.

The general idea is clear for modern Bibles. In the twenty-first century, people own Bibles that contain more than what they consider canonical, and they know which parts count as canonical because they’ve got a concept of canon in their heads. No one I know considers the maps in their Bibles canonical, or the cross references or the introductions or essays or notes. Some people own Bibles with apocrypha despite their strong adherence to the Protestant biblical canon; they would tell you that not everything in their Bible is canonical. But if you picked up their Bible, you wouldn’t be able to tell which parts they consider noncanonical.

So it has always been.

Hugh of Saint Victor in the twelfth century said that not everything “in the Old Testament” is “included in the canon,” such as the Wisdom of Solomon (in Veteri Testamento, ut diximus, quidam libri sunt qui non scribuntur in canone; PL 175.16a; trans. van Liere 2013: 219).

A few centuries later, the Scandinavian Lutheran Niels Hemmingsen (1555) averred that (in the summary of Hayes 2008: 990) “writings could be found in the Bible but not be canonical (authoritative).”

The same sort of idea is expressed in the anti-Catholic Russian Orthodox Archbishop Feofan Prokopovich (1681–1726): “There is no doubt that not all the books contained in this volume that is called the Bible are canonical. There are some in it which are not guaranteed by any divine testimony, which are not canonical, and which are given the name Apocrypha” (as quoted by Lash 2007: 228).

I grant that these three examples—the only examples I can cite right now that are so explicit about the point I want to make—all come from people who could be considered somewhat unusual with regard to the biblical canon they advocate. Modern scholars might object that these three authors from the second millennium do not have much in common with early Christians in their views on the biblical canon.

What about Athanasius? The fourth-century bishop of Alexandria produced what is probably the most famous canon list today, since it provides the earliest preserved list of books for the New Testament that matches the now-dominant 27-book New Testament (Festal Letter 39 in Gallagher and Meade 2017: 118–29). As for the Old Testament, Athanasius more-or-less stood with every other Greek canon list we have from the fourth century—and the few that we have from earlier centuries, such as those of Origen and Melito of Sardis—in limiting his Old Testament to the twenty-two books of the Jews (see the other lists in ch. 3 of Gallagher and Meade 2017), though Athanasius did exclude Esther from the canon. According to Athanasius, such canonical books are

the springs of salvation, so that someone who thirsts may be satisfied by the words they contain. In these books alone the teaching of piety is proclaimed. Let no one add or subtract anything from them. (§19 at Gallagher and Meade 2017: 124; translation adapted from Brakke 2010)


But Athanasius did not think that these canonical books were the only writings a Christian should read. He continues:

But for the sake of greater accuracy, I add this, writing from necessity. There are other books, outside of the preceding, which have not been canonized, but have been prescribed by the ancestors to be read to those who newly join us and want to be instructed in the word of piety: the Wisdom of Solomon, the Wisdom of Sirach, Esther, Judith, Tobit, the book called Teaching of the Apostles, and the Shepherd. Nevertheless, beloved, the former books are canonized; the latter are (only) read; and there is no mention of the apocryphal books. (§§ 20–21)


Athanasius discusses three categories of books here: (1) the canonized books; (2) the books that are not canonized but still read by Christians, especially those new to the faith; and (3) apocrypha. Obviously, Athanasius does not define the word “apocrypha” the same way as Protestants do; Athanasius means books like 1 Enoch or the Gospel of Thomas, and these are books that Athanasius thinks would not be valuable to a Christian.

The middle category of books—the valuable but not canonized books—include some of the books Protestants consider the Old Testament Apocrypha (but not Maccabees), one book included in the Jewish Bible (Esther), and a couple of books included in the Apostolic Fathers (as the books in that modern collection have been known for a few centuries now).

Now, to go back to manuscripts. It has often been pointed out that the Old Testament of Codex Vaticanus corresponds precisely with the Old Testament books included in Athanasius’ first two categories. As for the New Testament, we can’t be sure, because Vaticanus breaks off in Hebrews, so which books appeared after that must remain in some ways a mystery. Now, a question about which we can only take educated guesses: would Athanasius have objected to Codex Vaticanus containing Wisdom of Solomon? Or Esther? Or Tobit? After all, Athanasius insisted that these books were not a part of the biblical canon. Then again, he also insisted that these same books were useful to Christians. The latter sentiment leads me to assume Athanasius would not have objected to a biblical manuscript that included these non-canonical books, but may have even desired it.

And that means that the contents of such a biblical manuscript would not have corresponded to Athanasius’ biblical canon. Or, to echo the words of Feofan Prokopovich, not all the books in the Bible are in the canon.

Canon is a concept, an idea. If we equate the Bible with the canon, then the Bible is also a concept. But often we define the Bible as a physical object, in which case the Bible is not the canon. The biblical canon is not a physical object.

Quotations: Canon through Citation?

Ancient Jews and Christians quoted the Bible a lot, and these quotations provide extremely helpful information regarding the development of the biblical canon. But lists of quoted books, even lists of books quoted as scripture, are not the same as canon lists.

Once again, Athanasius provides a good example. Remember that Athanasius did not consider Wisdom of Solomon to be canonized, and yet he cites the work several times in his writings, three times under the title graphē (C. Gent. 11; 17; C. Ar. 2.79; cf. Leemans 1997). He treats the Shepherd of Hermas similarly; in one passage (Decr. 18.3), he quotes Herm. Mand. 1.1 (26.1) with this introduction: “and in the Shepherd it is written (γέγραπται), since they [= the Eusebians] bring forward even this book, though it is not in the canon.” This passage (Decr. 18.3) is the very one that scholars often point to as providing the earliest attestation of the word kanōn used in reference to the biblical canon (Metzger 1987: 292). Athanasius excludes the Shepherd from the canon, and then quotes it with the introductory term γέγραπται.

The list of writings quoted by Athanasius is not equivalent to Athanasius’ canon. The list of writings quoted “as Scripture” by Athanasius is not equivalent to Athanasius’ canon. We might consider this idea non-sensical: what could be the difference between Scripture and canon? But scholars have distinguished the two concepts for decades now, and Athanasius did, too (though in a different way). The canonized books are “the springs of salvation … [wherein] alone the teaching of piety is proclaimed.” Their number is subject to neither addition or subtraction (Ep. fest. 39.19; quoted above). The books in the middle category (not canonized but read) have been traditionally assigned (according to Athanasius) for elementary instruction “in the word of piety” (§20).

I interpret these sentiments in harmony with other patristic evidence to mean that a faithful Christian should never disagree with a canonized book (it is absolutely authoritative), though some other books are very helpful for understanding aspects of the faith—they provide good, basic introductions to Christian theology and morality—but their authority is not absolute (there might be occasion to set them aside; see further Gallagher 2019). Maybe we can think about Athanasius’ view of Wisdom of Solomon and the Shepherd of Hermas as something like the reception of Mere Christianity among many modern Christians.

Some Problems with Canon Lists

I have argued that the canon lists provide our primary point of entry into thinking about which writings ancient Christians considered canonical. That is not to say that the interpretation of the canon lists entails no problems. I end this essay with reflections on just two of these difficulties.

(1) The representative nature of the canon lists.

It is safest to say that a particular author’s canon list represents the canon of that particular author. There were disagreements on the precise limits of the biblical canon in antiquity. (Such disagreements have never ended.) The canon lists themselves are products of these disagreements; there would have been less need to produce such lists if there were universal agreement on what should be included. No patristic author had the authority to end all discussion on the matter. The Christian biblical canon was not definitively settled in the fourth century.

Let me say, however, that there is an impressively consistent core of books across the spectrum of canon lists. In the fourth century, among Christians both Arian and pro-Nicene and everywhere in between, arguments did not hinge on which books someone accepted as canonical. Everyone accepted the Pentateuch as canonical, and the Four Gospels, and the letters of Paul (with some uncertainty about Hebrews), and much else. Just because the canon was not definitively settled across the board—people could still disagree about the status of Tobit—does not mean people were flying completely blind. Nobody disputed that Isaiah was God’s word; nobody would have been willing to respond to an Isaian prooftext from their theological opponent by saying that Isaiah’s words were wrong or irrelevant.

There has been a long-standing scholarly dispute about the best way to define “canon”: whether as a list of authoritative books or as an authoritative list of books (to echo Metzger 1987: 282). A similar distinction is sometimes labeled “Canon 1” (= open canon) and “Canon 2” (= closed canon).

However helpful these distinctions may be, I’m not all that interested in them. When it comes to the canon lists, we would of course recognize that these lists represent “Canon 2”; they are authoritative lists of books—but, only for the specific author drafting the list, and whoever happens to grant to that author authority sufficient to determine their own canon. Athanasius did not settle the canon for the whole church. His canon list represents the canon of Athanasius and those within his jurisdiction. Same for Augustine, Jerome, and even Pope Innocent I.

And even limiting the authority of the canon list to its own author, we’re not out of trouble. We’ve already seen that Athanasius grants some version of authority to works outside his list of canonized books. He’s not the only one to do this (I again point the reader to my article, Gallagher 2019). When in a single passage Athanasius denies canonical authority to a writing and cites that same writing authoritatively, the good bishop has presented us with an intriguing notion of authority that transcends (or combines?) the usual distinctions between Canon 1 and Canon 2.

(2) The words on the page.

Sometimes the very words constituting a canon list are difficult to interpret. If we’re looking at a Christian canon list, we have a pretty good idea of what they meant by “Genesis” or “Isaiah” or “Luke.” But especially for certain Old Testament books, there is some ambiguity. This applies particularly to Esther, Daniel, Jeremiah, and Ezra, each of which exists in multiple versions, versions that differ quite substantially.

Here is one instance in this discussion where biblical manuscripts prove very helpful—essential, really. When a canon list mentions “Daniel,” we should almost always assume that this title referred (in the mind of the composer of the canon list) to the long version of Daniel, inclusive of the deuterocanonical additions (Susanna, Bel & the Dragon, and the Prayer of Azariah and the Hymn of the Three Young Men). We can make this assumption because the version of Daniel known from the Christian manuscripts is this long form.

This example raises questions, such as: to what extent would a patristic author (or someone today) have thought that a particular textual form of a book was canonical? That’s a difficult question; in regard to the additions to Daniel, sometimes (in later lists) these additions appear separately within canon lists (i.e., Susanna listed as a separate item; see the ninth-century list of Nicephorus), so we can say that at least some people thought of these texts as perhaps not integral to Daniel and yet still canonical. Athanasius specifies in his list that the item titled “Jeremiah” includes not only the material still today circulating under that name but also Baruch, Lamentations, and the Epistle of Jeremiah.

And then there’s Jerome’s Latin version of Daniel. Jerome translated from a Hebrew text that included none of the deuterocanonical additions. He translated these additions from Theodotion’s Greek text and prefixed an obelus (resembling a hyphen or dash) to their every line. In the preface to his translation he explains that these additions are not found in the Hebrew text, and that the obelus is intended to “slay” them. When readers encountered this version of Daniel, with the additions preceded by obelus, what did they think? Were the additions canonical? Latin manuscripts often do not transmit the obeli, such as the Codex Amiatinus from around 700, or Theodulf’s Bibles from the next century, but these Bibles do preserve Jerome’s notes explaining the absence of the additions from the Hebrew Bible. Alcuin’s Bibles—contemporary with Theodulf—do at least sometimes display the obeli in Daniel.

When a canon list simply says “Daniel,” we are still left with questions about how the author of the list thought about the alternative versions transmitted under this one title.


The development of the Bible has attracted a great deal of scholarly and popular attention because it is a fascinating subject with vexing problems and surprising twists. The canon lists are an essential part of such study. Though at times difficult to interpret, they provide essential information on how ancient Christians parsed the status of the various religious books available to them.


Brakke, David. 2010. “A New Fragment of Athanasius’ Thirty-Ninth Festal Letter: Heresy, Apocrypha, and the Canon.” Harvard Theological Review 103: 47–66. 

Gallagher, Edmon L. 2019. “Origen on the Shepherd of Hermas.” Early Christianity 10: 201–15.

Gallagher, Edmon L., and John D. Meade. 2017. The Biblical Canon Lists from Early Christianity: Texts and Analysis. Oxford: Oxford University Press.

Hayes, John H. 2008. “Historical Criticism of the Old Testament Canon.” Pages 985–1005 in Hebrew Bible / Old Testament: The History of Its Interpretation. Edited by Magne Sæbø. Volume 2: From the Renaissance to the Enlightenment. Göttingen: Vandenhoeck & Ruprecht.

Lash, Ephrem. 2007. “The Canon of Scripture in the Orthodox Church.” Pages 217–32 in The Canon of Scripture in Jewish and Christian Tradition. Edited by Philip S. Alexander and Jean-Daniel Kaestli. Prahins: Éditions du Zèbre.

Leemans, J. 1997. “Athanasius and the Book of Wisdom.” Ephemerides Theologicae Lovanienses 73: 349–68.

Metzger, Bruce M. 1987. The Canon of the New Testament: Its Origin, Development, and Significance. Oxford: Oxford University Press.

Van Liere, Frans, trans. 2013. “Hugh of Saint Victor: On Sacred Scripture and Its Authors; The Diligent Examiner.” Pages 203–52 in Interpretation of Scripture: Theory. A Selection of Works of Hugh, Andrew, Richard and Godfrey of St Victor, and of Robert Melun. Edited by Franklin T. Harkins and Frans van Liere. Hyde Park: New City Press.  

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