This is the fifth collection of articles by Eliyahu Ashtor to be published by Variorum and focuses on the fundamental question of why, during the later Middle Ages, technology and industry declined, even collapsed, in the Muslim Levant, while simultaneously making enormous progress in the Christian West. An indefatigable researcher in archives all over the Mediterranean, Ashtor amassed quantities of data on this subject, and began to propose causal links between, on the one hand, demographic trends, types of political regime, economic policies and attitudes towards innovation, and on the other, the progress or decline of technology and industry. Although his work was cut short by his death in 1984, the information that Ashtor has made available, for instance on the sugar and the alkali industries, and the questions and hypotheses he has suggested will provide a vital basis for continuing research. The final article, dealing more specifically with the history of commerce, represents in effect a summation of the author’s views on the role of the Jews in the trade of the Mediterranean. La cinquieme collection d’articles d’Eliyahu Ashtor A A tre publiee par Variorum (pour les deux volumes encore disponibles, voir p.00) se concentre sur la raison fondamentale pour laquelle, durant le Bas Moyen Age, la technologie et l’industrie dans le Levant musulman etaient en declin, voire m A me en plein effondrement, alors qu’elles faisaient simultanement d’enormes progres dans l’Ouest chretien. Cherchiste infatiguable des archives mediterraneennes, Ashtor a amasse quantite d’informations A ce sujet et a commence A suggerer l’existence de lien de cause entre: d’une part, les tendances demongraphiques, les types de regimes politiques, la politique economique et les attitudes vis-A -vis du changement et, d’autre part, le progres ou le declin de la technologie et de l’industrie. Bien que son travail ait ete interrompu par sa mort en 1984,