The learned are not agreed as to the time when the Gospel of John was written; some dating it as early as the year 68, others as late as the year 98; but it is generally conceded to have been written after all the others.

In this quote, Simon Greenleaf, a legal scholar and one of the founding professors of Harvard Law School, addresses the dating of the Gospel of John in the New Testament. Greenleaf points out the disagreement among scholars, or the learned, regarding the exact time when this gospel was written. Some scholars believe it was written as early as 68 AD, while others place it as late as 98 AD. Despite these differences, it is widely accepted that the Gospel of John was written later than the other three gospels—Matthew, Mark, and Luke.

The origin of this statement is rooted in Greenleaf’s expertise in law and his scholarly interest in the historical validity of religious texts. He was known for applying legal principles to evaluate the evidence supporting the truth of the Gospels, which is reflected in his analysis of the differing views on when the Gospel of John was written. Greenleaf’s work is often cited in discussions of Christian apologetics, where historical evidence and scholarly debate play a key role in understanding the origins of biblical texts.

Greenleaf’s mention of the disagreement among scholars highlights the ongoing debate over the authorship and timeline of the Gospels. This discussion is significant because the dating of the Gospel of John helps establish its historical context, shedding light on how it relates to the other gospels. His observation that it is "generally conceded to have been written after all the others" reflects the general consensus among scholars that John's gospel was written later, possibly to address different theological concerns or audience needs.

Ultimately, the quote emphasizes the complexity of biblical scholarship and the uncertainty that can surround the dating of ancient texts. Greenleaf’s insight into the Gospel of John reflects the broader challenges of interpreting and dating historical documents, especially those with profound religious and cultural significance. The debate over the timing of its writing reveals the layers of history and interpretation that contribute to our understanding of foundational texts like the Gospel of John.