classes of people) spanning the lines of cleavage between nations or states that lead to war. One version of this is the idea of promoting international understanding between nations through the international mobility of students – an idea most powerfully advanced by Cecil Rhodes in the creation of the Rhodes Scholarships, and his successors such as J. William Fulbright. Another theory is that peace can be developed among countries on the basis of active management of water resources. Day Peace day was founded as a day to recognize, honour and promote peace. It is commemorated each year by United Nations members. Studies, rankings, and periods Peace and conflict studies Peace and conflict studies is an academic field which identifies and analyses violent and nonviolent behaviours, as well as the structural mechanisms attending violent and non-violent social conflicts. This is to better understand the processes leading to a more desirable human condition. One variation, Peace studies (irenology), is an interdisciplinary effort aiming at the prevention, de-escalation, and solution of conflicts. This contrasts with war studies (polemology), directed at the efficient attainment of victory in conflicts. Disciplines involved may include political science, geography, economics, psychology, sociology, international relations, history, anthropology, religious studies, and gender studies, as well as a variety of other disciplines. Measurement and ranking Although peace is widely perceived as something intangible, various organizations have been making efforts to quantify and measure it. The Global Peace Index produced by the Institute for Economics and Peace is a known effort to evaluate peacefulness in countries based on 23 indicators of the absence of violence and absence of the fear of violence. The last edition of the Index ranks 163 countries on their internal and external levels of peace. According to the 2017 Global Peace Index, Iceland is the most peaceful country in the world while Syria is the least peaceful one. Fragile States Index (formerly known as the Failed States Index) created by the Fund for Peace focuses on risk for instability or violence in 178 nations. This index measures how fragile a state is by 12 indicators and subindicators that evaluate aspects of politics, social economy, and military facets in countries. The 2015 Failed State Index reports that the most fragile nation is South Sudan, and the least fragile one is Finland. University of Maryland publishes the Peace and Conflict Instability Ledger in order to measure peace. It grades 163