Difficult problems are not solved by fleeing from or by concealing them; and yet many physicians, many philosophers attempt to solve the most burning questions of modern society after the manner of a child who by closing his eyes believes that he is fleeing from the dog that threatens him. To Dr. Monlau in Spain and Dr. Bergeret in France, who thought that they would be able to save society by abolishing prostitution, I replied in a few words which I wish to save from the shipwreck of the newspapers in order to gather them in the shadow of this book: "I have never wondered at finding philosophers who study man in Fichte or in Kant without having ever touched his palpitating body, or examined any of his fibers with the microscope; who advise the legislator to destroy in the social organism, with iron and fire, that livid and cancerous spot called prostitution; neither have I given the alarm or extolled it as a miracle when I heard the _auto-da-fé_ invoked against the houses of ill fame by moralists who have had the rare fortune of having been born without the sixth sense, or the still rarer merit of smothering it with the extinguisher of an iron will. But when I hear these intolerant cries from the mouth of a physician, I shake my head diffidently, and with a compassionate voice I ask myself: 'Is he really a physician? Has this moralist actually seen a man in convulsive delirium and cut into his cold and rigid flesh on the chilly marble slab of the anatomical cabinet? He who hurls the anathema at prostitution, is he really the physician who should act as a kind link between the legislator, who in man sees only a defendant to punish, and the philanthropist, who in him considers only an unhappy creature to heal and help?' "These and other questions I addressed to the illustrious Spanish physician Monlau when he proposed to his government the absolute suppression of the houses of ill fame; and then I had the pleasure of seeing my poor words printed in the progressive Spanish medical journals. Now I make the same reproach to Dr. Bergeret, who, in one of his memoirs on prostitution in the country places and small towns of France, went so far as to fling the anathema against that caustic wound which civilization has opened in the diseased flesh of the modern social organism; and I, with a sad air, repeat to the French physician a melancholy: '_Tu quoque, fili mi_?'