=1818.= In comparing the performance in Euclid with that in Arithmetic and Algebra there could be no doubt that Euclid had made the deepest and most beneficial impression: in fact it might be asserted that this constituted by far the most valuable part of the whole training to which such persons [students, the majority of which were not distinguished for mathematical taste and power] were subjected.--TODHUNTER, I. _Essay on Elementary Geometry; Conflict of Studies and other Essays (London, 1873), p. 167._ =1819.= In England the geometry studied is that of Euclid, and I hope it never will be any other; for this reason, that so much has been written on Euclid, and all the difficulties of geometry have so uniformly been considered with reference to the form in which they appear in Euclid, that the study of that author is a better key to a great quantity of useful reading than any other. --DE MORGAN, A. _Elements of Algebra (London, 1837), Introduction._ =1820.= This book [Euclid] has been for nearly twenty-two centuries the encouragement and guide of that scientific thought which is one thing with the progress of man from a worse to a better state. The encouragement; for it contained a body of knowledge that was really known and could be relied on, and that moreover was growing in extent and application. For even at the time this book was written--shortly after the foundation of the Alexandrian Museum--Mathematics was no longer the merely ideal science of the Platonic school, but had started on her career of conquest over the whole world of Phenomena. The guide; for the aim of every scientific student of every subject was to bring his knowledge of that subject into a form as perfect as that which geometry had attained. Far up on the great mountain of Truth, which all the sciences hope to scale, the foremost of that sacred sisterhood was seen, beckoning for the rest to follow her. And hence she was called, in the dialect of the Phythagoreans, “the purifier of the reasonable soul.”--CLIFFORD, W. K. _Lectures and Essays (London, 1901), Vol. 1, p. 354._ =1821.= [Euclid] at once the inspiration and aspiration of scientific thought.--CLIFFORD, W. K. _Lectures and Essays (London, 1901), Vol 1, p. 355._