1 The author’s preface to the twelfth edition is confined to pointing out the improvements etc., made in the eleventh. There is no new preface to the thirteenth edition of the original, which appeared in 1877.—TRANSLATOR. 2 “We shall never thoroughly understand the reason of customary law unless we also have a knowledge of that which is not customary. The one is connected and bound to the other. We have no slaves; why vex ourselves with questions about slaves?—Words worthy of a novice.” 3 “I am a man; I think nothing foreign to me that pertains to man.” 4 “That excellent and glorious philosophy.” 5 Introduction to the Civilistisches Magazin. _ 6 Dunoyer_, De la Liberté du Travail. _ 7 Cicero_, De Leg., I. 8 Discours Préliminaire du Code Civil. _ 9 Cicero_, De Leg., II, 4. “Legem neque hominum ingeniis excogitatam, nec scitum aliquod esse populorum, sed æternum quiddam quod universum mundum regeret, imperandi, prohibendique sapientia.” _Ibid._ 10 Revue de Législ. et de Jurispr. (1841, XIII, p. 39.) _Montesquieu_ says: “The relations of justice and equity are anterior to all positive laws.” 11 Mr. Wolowski translated the second edition of Roscher’s Principles into French, and prefixed the present essay thereto as a preface. Since Wolowski’s translation appeared, the original work has gone through eleven editions, been largely increased in size, and enriched with new notes, the result of nearly twenty additional years of research and thought. The thirteenth German edition, from which the present translation is made, is larger than the first by one hundred and seventy pages.—_Translator’s note._ 12 And he adds: “Animals which yield only to an impulse or blind instinct, come together only fortuitously or periodically and in a manner destitute of all morality. But in the case of men, reason is mixed up more or less with every act of their lives. Sentiment is found side by side with desire, and right succeeds instinct. I discover a real contract in the union of the two sexes.” It would be impossible to present a more complete or eloquent refutation of the definition of the Roman jurisconsults which debases marriage to the level of the promiscuous coming together of animals, and which limits the natural law to the law common to man and beast. “Jus naturale est quod natura omnia animalia docuit; nam jus istud non humani generis proprium, sed omnium animalium quæ in terra, quæ in mare nascuntur, avium quoque commune est. Hinc descendit maris atque feminæ conjunctio, quam nos matrimonium appellamus, hinc liberorum procreatio, hinc educatio; videmus etenim cætera quoque animalia, feras etiam, istius juris peritia censeri.” D. L. I. De Just. et Jure.