Collectio juris

Catherine Volpilhac-Auger

1According to the abbé Guasco, Montesquieu used to say that “obliged by his father to spend the day on the Code, he was so tired of it in the evening that to amuse himself he would start writing a Persian letter and it flowed from his pen without effort” (“obligé par son père de passer toute la journée sur le Code, il s’en trouvait le soir si excédé, que pour s’amuser, il se mettait à composer une lettre persane et que cela coulait de sa plume, sans étude”, Lettres familières, October 1752; OC, t. XXI). Thus would be constituted the birth certificate of the Collectio juris (or “law anthology”), a collection or work of formation, notes taken in the course of reading Roman law in depth, which constitutes the very apprenticeship of his profession as jurist. Montesquieu was destined for it by family vocation, from the time he was taken to receive from his uncle Jean-Baptiste de Secondat, who had no descendants, the charge of président à mortier in the parlement of Guyenne. But the difficult entry into the mysteries of Roman law proves to be much more important than what appears here in Montesquieu’s memories, or rather in the legend that built up through the Lettres familières. Without the Collectio juris, Montesquieu would not have acquired the Latin and juridical culture that constitutes the underpinnings of L’Esprit des lois; and if we might regret not finding in it the very germs of the great work, it is incontestable that it does give us the mould in which was formed a mind that would never forget the lessons of Roman law – even when he contests or critiques them.

2These six notebooks now held by the Bibliothèque Nationale de France, acquired in 1939, have been published for the first time by Iris Cox and Andrew Lewis in 2005 (the present article borrows much from their introduction). They were written for the most part during Montesquieu’s stay in Paris between 1709 and 1711. Having taken stock of the weakness of the teaching of law in Bordeaux, he felt the necessity of a more serious foundation (though it was not required by the difficulty of the entrance exam, which was a mere formality). Roman law then held capital importance: it was the “written law” (droit écrit) in France, dominant in part of the country (notably the south), though the partition between written and common law was not really explicit, so it could be applied in many cases in the role of “suppletory” law (droit supplétif). The complexity of the situation is touched upon in L’Esprit des lois: “Although common law is regarded in our country as containing a sort of opposition to Roman law, so that these two laws divide the territories, yet it is true that several dispositions of Roman law have entered our common law, especially when new versions of them were composed […]” (“Quoique le droit coutumier soit regardé parmi nous comme contenant une espèce d’opposition avec le droit romain, de sorte que ces deux droits divisent les territoires, il est pourtant vrai que plusieurs dispositions du droit romain sont entrées dans nos coutumes, surtout lorsqu’on en fit de nouvelles rédactions […]”, XXVIII, 45). What is the particular case of the Guyenne parlement, where Montesquieu was to practice? “The parlement of Bordeaux will always refuse to allow itself to be counted among the parlements of written law, on the grounds that it applies Roman law only in instances where the common law is silent.” (“Le parlement de Bordeaux refusera toujours de se laisser compter parmi les parlements de droit écrit motif pris de ce qu’il n’applique le droit romain que dans le silence de la coutume ”, Regnault, p. 83). Which is to say that it was but one element in Montesquieu’s “professional” training – but the comparison of common and Roman law, and the exploration of the Corpus juris civilis itself (a compilation of Roman law made at the order of Justinian, consisting of three parts: Digest, Code, and Institutes) constituted much more than a technical study.

3Montesquieu utilized one of numerous commented editions based on a text of Gothofredus (Godefroy), one of the great specialists of humanist juridical science (one of these editions, dated from 1612, was at La Brède: Catalogue, no. 705). The commentators (Dumoulin, Mornac, Ferrière, this last one more recent) play an important role: it is often to their interpretations that the remarks in the Collectio juris refer, as well as to eminent jurists like Cujas and Domat. The first three volumes contain notes and commentaries on the fifty books of the Digest, the next three on the twelve books of the Code (in a particularly detailed manner), as well as on forty-seven of the 168 Novelles (the absence of the Institutes should be noted); finally they present several contemporary lawsuits, from the jurisdiction of the Paris parlement: “Croisat v. Hori” (ca. 1705); “La Cour du Bois v. Vauvré” (1711); “the heirs of Pierre de … v. d’Authun and de La Baume”; “Nicolaï v. Nicolaï” (1710-1712); “Binet agaist Louis de ...”; the Duc de Sully, marquis de Rosny, v. one Pierre ...” (1711); “the archbishop of Reims v. the monks of Saint-Rémi de Reims” (1711); “Serre v. Élisabeth de La Prairie” (1711); anonymous, on a bequest to a daughter who entered a convent; several suits judged in Bordeaux between 1716 and 1721, when Montesquieu was sitting there, first as counselor, then as président à mortier. Notes on the common law of Britanny, on the “legal maxims” (maximes de droit) of the advocate-general Joly de Fleury, and various other texts were to be added. His annotation consists in citing, summarizing and commenting upon the source text, in Latin and in French, most often aided by the commentaries he had before him. What is more personal in this ensemble is the choice he makes of the extracts he comments upon. It is by following this path that we can hope to understand how Montesquieu trained himself by reading law books, by their interpretation; without this apprenticeship, his interest in French common law and the evolution of law proper to each nation, such as they appear in the final books of L’Esprit des lois, would doubtless not have been the same. Finally, this intimate knowledge of Roman law, collected when it was constituted as a corpus and renewed itself in Constantinople in the Eastern Empire of the sixth century, is doubtless not foreign to the severity with which he judged the man who had played such an important role, Justinian I: as compiler and as legislator, this Christian emperor, who did not grasp the spirit of law or that of his people and thought of nothing but his own interests, was the very example of what ought not to be done.

4Finally, since the Persian Letters appeared as the counterpoint or even the antidote to the dryness of the Collectio juris, let us return to them: Who can think that a kingdom which is the oldest and most powerful in Europe should have been governed for over ten centuries by laws that were not made for it? If the French had been conquered, this would not be difficult to understand; but they are the conquerors.
They abandoned the ancient laws made by their first kings in general assemblies of the nation; and what is most singular about that is that the Roman laws which they adopted instead were in part made and in part drafted by emperors who were contemporaries of their legislators. […]
It is true that quite recently they have written down some statutes of cities and provinces, but they are almost all taken from Roman law.
This abundance of laws adopted, and so to speak naturalized, is so great that it overwhelms both justice and judges. But these volumes of laws are nothing in comparison to the frightful army of glossers, commentators, and compilers, men as weak in the unsoundness of their minds as they are strong by their prodigious numbers.
That is not all. These foreign laws have introduced formalities that are a disgrace to human reason. It would be rather difficult to decide whether the form has become more pernicious when it entered into jurisprudence, or when it ensconced itself in medicine; whether it has caused more damage under the robe of a jurist than under the physician’s broad hat; and whether it has ruined more people in the former than it has killed in the latter. (LP, [‣]).

5These excessively harsh judgments for what was in fact to constitute the object of study for Montesquieu’s entire life perhaps offer ultimately the best confirmation of the testimony of Guasco. From the Collectio juris also come the spirit of law for which he was training himself as well as the Persian Letters, which offer their diversion and satire.



Bibliothèque nationale de France, NAF 12837-12842 (six volumes in-quarto).


Collectio juris, ed. Iris Cox et Andrew Lewis, OC, t. XI et XII, 2005.

Critical studies

Henri Regnault, Manuel d’histoire du droit français, 2nd ed., Paris : Recueil Sirey, 1947.

Iris Cox et Andrew Lewis, “Montesquieu observateur et étudiant en droit, 1709-1720”, in Montesquieu: les années de formation (1689-1720), ed. C. Volpilhac-Auger, Cahiers Montesquieu 5, 1999, p. 55-63.

Catherine Volpilhac-Auger, “Ex Oriente nox? Le paradoxe byzantin chez Montesquieu”, DHS 35 (2003),

Catherine Volpilhac-Auger, “De la Collectio juris à L’Esprit des lois: Justinien au tribunal de Montesquieu”, in Montesquieu, la justice, la liberté: hommage de Bordeaux à Montesquieu, Bordeaux: Académie des Sciences, Belles-lettres et Arts de Bordeaux, 2007, p. 35-43, (repris dans C. Volpilhac-Auger, Montesquieu : une histoire de temps, Lyon, ENS Éditions, 2017 [].