 A change in attitudes can be noticed already by the late 18th century. In 1759 d’Alembert called the problem of parallel lines “le scandale des éléments de géométrie.” In 1763, the dissertation of G. S. Klügel examined a large number of attempts to prove the parallel postulate, concluding that they were all faulty: the result can be proven on the basis of axioms "that are not clearer or more secure than Euclid’s," and thus Euclid was indeed right to include among the axioms "a proposition that cannot be demonstrated in correct form." Klügel's discussion called special attention to Saccheri’s work (1733) as the most detailed treatment in Modern times, and stimulated Lambert to do his own detailed work on the topic (1786). Later on, in 1816, Gauss restated in print that the constantly increasing number of attempts to prove the postulate do not fill the gap, and that one should honestly and openly admit that "in essence we have not come farther than Euclid 2000 years ago."