The enthusiasm shown during the first quest diminished after Albert Schweitzer's critique of 1906 in which he pointed out various shortcomings in the approaches used at the time. The second quest began in 1953 and introduced a number of new techniques, but reached a plateau in the 1970s. In the 1980s a number of scholars gradually began to introduce new research ideas, initiating a third quest characterized by the latest research approaches. Since the late 2000s, concerns have been growing about the usefulness of the criteria of authenticity.