-While some researchers would approach the study of the Court through an article by analysis and commentary, this approach would detract from the didactic goals and conceptual unity of the work. Instead, Professor Abello takes a thematic approach as he analyses the important features of the ICJ while taking into account their transition from the earlier PCIJ. The reader will understand the continuity betweeen the Permanent Court of International Justice, an organ of the League of Nations, and the International Court of Justice, the judicial organ of the United Nations. The Optional Clause of Compulsory Jurisdiction is a symbol of the continuity between the PCIJ and the ICJ-. Antonio Aljure.