It is not Fortune who governs the world, as we see from the history of the Romans.  There are general causes, moral or physical, which operate in every monarchy, raise it, maintain it, or overthrow it; all that occurs is subject to these causes; and if a particular cause, like the accidental result of a battle, has ruined a state, there was a general cause which made the downfall of this state ensue from a single battle.  In a word, the principal movement (l’allure principale) draws with it all the particular occurrences.

But if this excludes Fortune it also dispenses with Providence, design, and final causes; and one of the effects of the Considerations which Montesquieu cannot have overlooked was to discredit Bossuet’s treatment of history.

The Esprit des lois appeared fourteen years later.  Among books which have exercised a considerable influence on thought few are more disappointing to a modern reader.  The author had not the gift of what might be called logical architecture, and his work produces the effect of a collection of ideas which he was unable to co-ordinate in the clarity of a system.  A new principle, the operation of general causes, is enthroned; but, beyond the obvious distinction of physical and moral, they are not classified.  We have no guarantee that the moral causes are fully enumerated, and those which are original are not distinguished from those which are derived.  The general cause which Montesquieu impresses most clearly on the reader’s mind is that of physical environment—­geography and climate.

The influence of climate on civilisation was not a new idea.  In modern times, as we have seen, it was noticed by Bodin and recognised by Fontenelle.  The Abbe de Saint-Pierre applied it to explain the origin of the Mohammedan religion, and the Abbe Du Bos in his Reflexions on Poetry and Painting maintained that climate helps to determine the epochs of art and science.  Chardin in his Travels, a book which Montesquieu studied, had also appreciated its importance.  But Montesquieu drew general attention to it, and since he wrote, geographical conditions have been recognised by all inquirers as an influential factor in the development of human societies.  His own discussion of the question did not result in any useful conclusions.  He did not determine the limits of the action of physical conditions, and a reader hardly knows whether to regard them as fundamental or accessory, as determining the course of civilisation or only perturbing it.  “Several things govern men,” he says, “climate, religion, laws, precepts of government, historical examples, morals, and manners, whence is formed as their result a general mind (esprit general).”  This co-ordination of climate with products of social life is characteristic of his unsystematic thought.  But the remark which the author went on to make, that there is always a correlation between the laws of a people and its esprit general, was important.  It pointed to the theory that all the products of social life are closely interrelated.