Bossuet had dealt nobly with Roman history, but in the spirit of a theologian expounding the course of Divine Providence in human affairs. Montesquieu studied the operation of natural causes. His knowledge, indeed, was incomplete, but it was the knowledge afforded by the scholarship of his own time. The love of liberty, the patriotic pride, the military discipline, the education in public spirit attained by discussion, the national fortitude under reverses, the support given to peoples against their rulers, the respect for the religion of conquered tribes and races, the practice of dealing at one time with only a single hostile power, are pointed out as contributing to the supremacy of Rome in the ancient world. Its decadence is explained as the gradual result of its vast overgrowth, its civil wars, the loss of patriotism among the soldiery engaged in remote provinces, the inroads of luxury, the proscription of citizens, the succession of unworthy rulers, the division of the Empire, the incursion of the barbarians; and in treating this portion of his subject Montesquieu may be said to be wholly original. A short Dialogue de Sylla et d'Eucrate may be viewed as a pendant to the Considérations, discussing a fragment of the subject in dramatic form. Montesquieu's desire to arrive at general truths sometimes led him to large conclusions resting on too slender a basis of fact; but the errors in applying his method detract only a little from the service which he rendered to thought in a treatment of history at least tending in the direction of philosophic truth.
The whole of his mind—almost the whole of his existence—is embodied in the Esprit des Lois (1748). It lacks the unity of a ruling idea; it is deficient in construction, in continuity, in cohesion; much that it contains has grown obsolete or is obsolescent; yet in the literature of eighteenth-century thought it takes, perhaps, the highest place; and it must always be precious as the self-revealment of a great intellect—swift yet patient, ardent yet temperate, liberal yet the reverse of revolutionary—an intellect that before all else loved the light. It lacks unity, because its author's mind was many-sided, and he would not suppress a portion of himself to secure a factitious unity. Montesquieu was a student of science, who believed in the potency of the laws of nature, and he saw that human society is the product of, or at least is largely modified by, natural law; he was also a believer in the power of human reason and human will, an admirer of Roman virtue, a citizen, a patriot, and a reformer. He would write the natural history of human laws, exhibit the invariable principles from which they proceed, and reduce the study of governments to a science; but at the same time he would exhibit how society acts upon itself; he would warn and he would exhort; he would help, if possible, to create intelligent and patriotic citizens. To these intentions we may add another—that of a criticism, touched with satire, of the contemporary political and social arrangements of France.
And yet again, Montesquieu was a legist, with some of the curiosity of an antiquary, not without a pride in his rank, interested in its origins, and desirous to trace the history of feudal laws and privileges. The Esprit des Lois is not a doctrinaire exposition of a theory, but the record of a varied life of thought, in which there are certain dominant tendencies, but no single absolute idea. The forms of government, according to Montesquieu, are three—republic (including both the oligarchical republic and the democratic), monarchy, despotism. Each of these structural arrangements requires a principle, a moral spring, to give it force and action: the popular republic lives by virtue of patriotism, public spirit, the love of equality; the aristocratic republic lives by the spirit of moderation among the members of the ruling class; monarchy lives by the stimulus of honour, the desire of superiority and distinction; despotism draws its vital force from fear; but each of these principles may perish through its corruption or excess. The laws of each country, its criminal and civil codes, its system of education, its sumptuary regulations, its treatment of the relation of the sexes, are intimately connected with the form of government, or rather with the principle which animates that form.
Laws, under the several forms of government, are next considered in reference to the power of the State for purposes of defence and of attack. The nature of political liberty is investigated, and the requisite separation of the legislative, judicial, and administrative powers is exhibited in the example set forth in the British constitution. But political freedom must include the liberty of the individual; the rights of the citizen must be respected and guaranteed; and, as part of the regulation of individual freedom, the levying and collection of taxes must be studied.
From this subject Montesquieu passes to his theory, once celebrated, of the influence of climate and the soil upon the various systems of legislation, and especially the influence of climate upon the slave system, the virtual servitude of woman, and the growth of political despotism. Over against the fatalism of climate and natural conditions he sets the duty of applying the reason to modify the influences of external nature by wise institutions. National character, and the manners and customs which are its direct expression, if they cannot be altered by laws, must be respected, and something even of direction or regulation may be attained. Laws in relation to commerce, to money, to population, to religion, are dealt with in successive books.
The duty of religious toleration is urged from the point of view of a statesman, while the discussions of theology are declined. Very noteworthy is the humble remonstrance to the inquisitors of Spain and Portugal ascribed to a Jew of eighteen, who is supposed to have perished in the last auto-da-fé. The facts of the civil order are not to be judged by the laws of the religious order, any more than the facts of the religious order are to be judged by civil laws. Here the great treatise might have closed, but Montesquieu adds what may be styled an historical appendix in his study of the origin and development of feudal laws. At a time when antiquity was little regarded, he was an ardent lover of antiquity; at a time when mediæval history was ignored, he was a student of the forgotten centuries.
Such in outline is the great work which in large measure modified the course of eighteenth-century thought. Many of its views have been superseded; its collections of facts are not critically dealt with; its ideas often succeed each other without logical sequence; but Montesquieu may be said to have created a method, if not a science; he brought the study of jurisprudence and politics, in the widest sense, into literature, laicising and popularising the whole subject; he directed history to the investigation of causes; he led men to feel the greatness of the social institution; and, while retiring from view behind his work, he could not but exhibit, for his own day and for ours, the spectacle of a great mind operating over a vast field in the interests of truth, the spectacle of a great nature that loved the light, hating despotism, but fearing revolution, sane, temperate, wisely benevolent. In years tyrannised over by abstract ideas, his work remained to plead for the concrete and the historical; among men devoted to the absolute in theory and the extreme in practice, it remained to justify the relative, to demand a consideration of circumstances and conditions, to teach men how large a field of reform lay within the bounds of moderation and good sense.
The Esprit des Lois was denounced by Jansenists and Jesuits; it was placed in the Index, but in less than two years twenty-two editions had appeared, and it was translated into many languages. The author justified it brilliantly in his Défense of 1750. His later writings are of small importance. With failing eyesight in his declining years, he could enjoy the society of friends and the illumination of his great fame. He died tranquilly (1755) at the age of sixty-six, in the spirit of a Christian Stoic.