Italian literature can boast of two very valuable books on the physiology of pain. The first was written by Professor Filippo Lussana in 1860, and dedicated to Dr. Paolo Mantegazza, 'who was writing his celebrated “Physiology of Pleasure” when the joyous spring of his twenty-second year smiled upon the author.’ Twenty years later, in 1880, Paolo Mantegazza also published a valuable book on the 'Physiology of Pain.’ The merits of this book are great, and it is perhaps one of his greatest achievements in the field of physiology, but science has since made such rapid progress, that it would be well if a third volume were added to the group, developing the anatomical and physiological part, illustrating by instantaneous photographs the most characteristic movements and expressions of pain, and subjecting to a severe criticism the most celebrated pictures and statues of the various schools. I cherish the wish that Paolo Mantegazza, who was my master, and one of the greatest popularisers of science, may find time to complete and rejuvenate his work, for who else would find courage to take a place at his side, and to glean where he has reaped? VIII The art of the future, comprising all visible nature within its limits, will find a great and terrible potency of effect in the expression of pain. The difficulties, certainly, are here much greater than in the calm reproduction of the ideally beautiful, and those painters and sculptors who wish to grapple with the problem of the expression of pain must train themselves by the study of reality, and arm themselves with anatomical and physiological knowledge of which antique art gives us no example. I believe that, with the advance of a scientific criticism nurtured on an accurate knowledge of physiology, and intimately acquainted with the functions of the muscles, we shall one day recognise that the Greeks of the epoch of Phidias and Praxiteles were unequal to the effectual reproduction of violent passions.