From the Oral Tradition to Our Gospels
We know that Jesus died when he was still young and that he died without having written anything. Jesus had dedicated most of his time to forming the twelve apostles whom he had chosen. They lived with him, as was the custom of disciples with Jewish teachers. Jesus had them learn his teaching by heart. Instead of multiplying discourses, Jesus repeated the essential truths in many ways. We cannot doubt that, after the days of Pentecost, their concern was to give form to these instructions of Jesus, which were to be the catechesis of the early Church.
At the beginning the apostles witnessed to what they had seen and heard. Gradually there emerged a need to have a written record of their testimony to safeguard the memory: we ourselves often do this when, during a meeting, the sharing of the participants is recorded for the benefit of those not present.
The Christian communities of Palestine spoke Aramaic or Hebrew according to regions and environment. It follows that the first accounts were drawn up in these two languages. Gradually the texts referring to what Jesus said and did were regrouped; in this way the first Christian communities passed from an oral testimony to a written text: that of the Gospels.
At that time the Greek speaking Christian communities had become a majority and primitive texts were translated into that language.