Twiss, II. §§ 1-3--Ullmann, §§ 148-150--Bulmerincq in Holtzendorff, IV. pp. 5-12--Heffter, §§ 105-107--Rivier, II. § 57--Bonfils, No. 930--Despagnet, No. 469--Pradier-Fodéré, IV. Nos. 2580-2583--Calvo, III. §§ 1670-1671--Martens, II. §§ 101-102--Fiore, II. Nos. 1192-1198, and Code, No. 1246--Wagner, _Zur Lehre von den Streiterledigungsmitteln des Völkerrechts_ (1900.) [Sidenote: Legal and political International Differences.] § 1. International differences can arise from a variety of grounds. Between the extremes of a simple and comparatively unimportant act of discourtesy committed by one State against another, on the one hand, and, on the other, so gross an insult as must necessarily lead to war, there are many other grounds varying in nature and importance. State differences are correctly divided into legal and political. Legal differences arise from acts for which States have to bear responsibility, be it acts of their own or of their Parliaments, judicial and administrative officials, armed forces, or individuals living on their territory.[1] Political differences are the result of a conflict of political interests. But although this distinction is certainly theoretically correct and of practical importance, frequently in practice a sharp line cannot be drawn. For in many cases States either hide their political interests behind a claim for an alleged injury, or make a positive, but comparatively insignificant, injury a pretext for the carrying out of political ends. Nations which have been for years facing each other armed to the teeth, waiting for a convenient moment to engage in hostilities, are only too ready to obliterate the boundary line between legal and political differences. Between such nations a condition of continuous friction prevails which makes it difficult, if not impossible, in every case which arises to distinguish the legal from the political character of the difference. [Footnote 1: See above, vol. I. § 149.] [Sidenote: International Law not exclusively concerned with Legal Differences.]