It is unprofitable to indulge in much speculation concerning Lieber's sources for the Code. Since he had been a student of the law of war for at least a quarter of a century before the Instructions were promulgated, his primary source was Lieber reinforced with the notes and files that he had painstakingly built up during his teaching career. Under such circumstances, one can only mention his likes and dislikes. Chief among the latter were both Lawrence's Wheaton and “old” Vattel, whom he characterized as “Father Namby-Pamby”. Halleck's International Law was naturally looked upon with great favor, the more so because Halleck had drawn on Lieber's Political Ethics. Lieber probably relied heavily on Heffter's Das Europäische Völkerrecht der Gegenwart. He also consulted Grotius, Bynkershoek, and Pufendorff among the classical writers. In his library or mentioned in his works are books by a host of names, many of them long since forgotten : Zachariae, Trendlenburg, von Martens, Phillimore, Mackintosh, Whewell, Foelix, von Mohl, Bluntschli (a close friend of Lieber), Bernard, Kennedy, Klüber, Pinheiro-Ferreira, Kent, and Theodore Dwight Woolsey.