Size does matter when it comes to classifying the prophetic books of the Bible.
The distinction between minor and major prophets goes back a long time. As the fifth-century Christian theologian Augustine says in The City of God 18:29, “The prophet Isaiah is not in the book of the twelve prophets called minor (prophetae minores) because their discourses are short.” Back then the Latin word minor meant that something was smaller in some way while major was something relatively bigger. In this case, the subject in comparison was length.
But Augustine’s widely accepted explanation does raise another question: why does he refer to one book instead of twelve? Could this have been a case of major-prophet envy?
The answer lies in yet another ancient language. In the Hebrew Scriptures, the Minor Prophets are twelve -- count ‘em, twelve! -- books in one, conveniently titled “The Book of the Twelve.” Biblical scholars agree that this reflects the fact that in Jewish tradition, the texts have since long been written on a single scroll. This theory proves how easy biblical scholarship can be if you pick the right topic.
According to Kimchi (the medieval rabbi, not the national dish of Korea), the reason for collecting all of the minor prophets on one long scroll is to keep them from getting lost, which would be easy to do if each one was written separately on a smaller scroll. Let it not be said that medieval rabbis lacked a sense of humor.
Nowadays “The Book of the Twelve” is commonly shortened to “The Twelve,” not to be confused with the people who spread the vampire plague in Justin Cronin’s Passage trilogy.