MERCANTILE INVENTIONS. It began to be recognized, in spite of the preaching of the mendicant orders, that poverty is the source of crime, the obstruction to knowledge; that the pursuit of riches by commerce is far better than the acquisition of power by war. For, though it may be true, as Montesquieu says, that, while commerce unites nations, it antagonizes individuals, and makes a traffic of morality, it alone can give unity to the world; its dream, its hope, is universal peace. MEDICAL IMPROVEMENTS. Though, instead of a few pages, it would require volumes to record adequately the ameliorations that took place in domestic and social life after science began to exert its beneficent influences, and inventive talent came to the aid of industry, there are some things which cannot be passed in silence. From the port of Barcelona the Spanish khalifs had carried on an enormous commerce, and they with their coadjutors--Jewish merchants--had adopted or originated many commercial inventions, which, with matters of pure science, they had transmitted to the trading communities of Europe. The art of book-keeping by double entry was thus brought into Upper Italy. The different kinds of insurance were adopted, though strenuously resisted by the clergy. They opposed fire and marine insurance, on the ground that it is a tempting of Providence. Life insurance was regarded as an act of interference with the consequences of God's will. Houses for lending money on interest and on pledges, that is, banking and pawnbroking establishments, were bitterly denounced, and especially was indignation excited against the taking of high rates of interest, which was stigmatized as usury--a feeling existing in some backward communities up to the present day. Bills of exchange in the present form and terms were adopted, the office of the public notary established, and protests for dishonored obligations resorted to. Indeed, it may be said, with but little exaggeration, that the commercial machinery now used was thus introduced. I have already remarked that, in consequence of the discovery of America, the front of Europe had been changed. Many rich Italian merchants and many enterprising Jews, had settled in Holland England, France, and brought into those countries various mercantile devices. The Jews, who cared nothing about papal maledictions, were enriched by the pontifical action in relation to the lending of money at high interest; but Pius II., perceiving the mistake that had been made, withdrew his opposition. Pawnbroking establishments were finally authorized by Leo X., who threatened excommunication of those who wrote against them. In their turn the Protestants now exhibited a dislike against establishments thus authorized by Rome. As the theological dogma, that the plague, like the earthquake, is an unavoidable visitation from God for the sins of men, began to be doubted, attempts were made to resist its progress by the establishment of quarantines.