What is the Letter of Eusebius (Epistula ad Carpianum)?

Eusebius of Caesarea (260—339 AD) was a key leader in the early church. He was the bishop of Caesarea, a church historian, and a Bible scholar. Eusebius is also known for creating a system for comparing the four New Testament Gospels. “The Letter of Eusebius” is a letter he wrote to a man named Carpianus about the system. In the letter, Eusebius organizes parallel passages in Matthew, Mark, Luke, and John.

Along with men like Ignatius (c. 35—107 AD), Irenaeus (c. 130—202 AD), and Augustine (354—430 AD), Eusebius is one of the early church fathers. Only a few leaders from the early church have this title, which recognizes their impact on Christian history. Eusebius was a key figure in discerning the biblical canon—the books God inspired and included in the Bible.

As part of his work on the Bible, Eusebius spent considerable time reading the Gospels. His study included their parallels and apparent discrepancies. Scholars today call this process harmonizing—explaining how parallel passages align. A harmony of the Gospels, or any other parallels in Scripture, does not ignore differences but explains how they can be true at the same time.

Eusebius developed a unique method for studying parallel passages in the Gospels. Today, his system is known as the “Eusebian Canons.” The method arranges biblical passages into numbered sections and groups them in columns. The resulting display looks like a table. These tables serve as visual aids that help readers easily identify and compare parallel passages.

In the letter, Eusebius writes that he was not the first to develop a system for studying Gospel parallels. However, his version was better because people could either read each Gospel in order or study them in light of parallel passages. A numbering system next to each passage identified the parallel passages in other books. This system was an early form of cross-referencing, a feature found in many Bibles today.

The Gospels were foundational documents for the early church. Christian leaders didn’t see the differences between the four books as problematic. The church considered it a blessing to have four testimonies about Jesus’ life and ministry. They worked to solve discrepancies among them, not erase them. In many ways, having multiple accounts added credibility to the stories, since all four Gospel writers were eyewitnesses or used eyewitness accounts as sources.

Harmonizing parallel passages of Scripture is helpful for those who enjoy studying the Bible. First, it helps readers understand the whole story. Different writers may tell the same story from different perspectives, including distinct details, or write a longer or shorter account. For example, harmonizing the accounts of Matthew’s calling helps readers see that the tax collector called by Jesus is the same person referred to by two different names. Matthew’s Gospel calls him “Matthew,” while Mark and Luke refer to him as “Levi” (Matthew 9:9; Mark 2:14; Luke 5:27–28).

Another way harmonizing Scripture helps Bible readers is that it answers claims that it contains contradictions. By comparing the accounts, readers can see that differences in a story do not mean one version is wrong. For example, Matthew records that Jesus healed two blind men near Jericho, while Mark mentions one, focusing on the man named Bartimaeus (Matthew 20:29–34; Mark 10:46–52). Studying these passages together reveals there are no contradictions.

In 2 Timothy 2:15, Paul writes, “Do your best to present yourself to God as one approved, a worker who does not need to be ashamed and who correctly handles the word of truth.” Christians are known for their love of Bible study, and tools that aid in passage comparison can help them handle God’s Word correctly. Men like Eusebius helped people in his era study Scripture and, in many ways, laid the foundation for future believers to do so as well.