July 15, 1519 was the last day of the Leipzig Disputation. Schaff remarks
Luther himself was greatly dissatisfied, and regarded the disputation as a mere waste of time. He made, however, a deep impression upon younger men, and many students left Leipzig for Wittenberg. After all, he was more benefited by the disputation and the controversies growing out of it, than his opponents.
The importance of this theological tournament lies in this: that it marks a progress in Luther’s emancipation from the papal system. Here for the first time he denied the divine right and origin of the papacy, and the infallibility of a general council. Henceforward he had nothing left but the divine Scriptures, his private judgment, and his faith in God who guides the course of history by his own Spirit, through all obstructions by human errors, to a glorious end. The ship of the Reformation was cut from its moorings, and had to fight with the winds and waves of the open sea.
So, what may seem a waste of time to you may be a help to someone else…