A gospel harmony is an attempt to compile the Christian canonical gospels into a single account. This may take the form either of a single, merged narrative, or a tabular format with one column for each gospel, technically known as a "synopsis", although the word 'harmony' is often used for both. Harmonies are constructed to establish a chronology of events in the life of Jesus depicted in the canonical gospels, to better understand how the accounts relate to each other, or to establish events in the life of Jesus.
The construction of harmonies has always been favoured by more conservative scholars. Students of higher criticism, on the other hand, see the divergences between the Gospel accounts as reflecting the construction of traditions by the early Christian communities. In the modern era, attempts to construct a single story have largely been abandoned in favour of laying out the accounts in parallel columns for comparison, to allow critical study of the differences between them.
The earliest known harmony is the Diatessaron by Tatian in the 2nd century and variations based on the Diatessaron continued to appear in the Middle Ages. The 16th century witnessed a major increase in the introduction of Gospel harmonies and the parallel column structure became widespread. At this time visual representations also started appearing, depicting the Life of Christ in terms of a "pictorial gospel harmony", and the trend continued into the 19th–20th centuries.
A Gospel harmony is an attempt to collate the Christian canonical gospels into a single gospel account. Gospel harmonies are constructed and studied by scholars to establish a coherent chronology of the events depicted in the four canonical gospels in the life of Jesus, to better understand how the accounts relate to each other, and to critically evaluate their differences.
One approach to harmonizing consists of merging the stories into a single narrative, although as John Barton points out, it is impossible to construct a single account from the four Gospels without changing the individual accounts. This approach, almost as old as the gospels themselves, has largely been abandoned in the modern era. Another approach is that of rationalisation – attempting to show that inconsistencies between Gospel accounts are only apparent, an approach Barton says is associated, in the English-speaking world at least, with fundamentalism. A major problem with harmonizing the accounts is that events are often described in a different order – the Synoptic Gospels, for instance, describe Jesus overturning tables in the Temple at Jerusalem in the last week of his life, whereas the Gospel of John only records a counterpart event towards the beginning of Jesus's ministry. Harmonists must either choose which they think is correct, or conclude that separate events are described. Lutheran Theologian Andreas Osiander, for instance, proposed in Harmonia evangelica (1537) that Jesus must have been crowned with thorns twice, and that there were three separate episodes of cleansing of the Temple. A similar problem arises with the centurion whose servant is healed, at a distance. In the Matthew Gospel he comes to Jesus, in the Luke version he sends Jewish elders. Since these are clearly describing the same event, the harmonist must decide which is the more accurate description.