Catholic social doctrine. Of particular importance were his 1981 encyclical Laborem exercens and Centesimus annus in 1991. While not endorsing any particular political agenda, the church holds that this teaching applies in the public (political) realm, not only the private. Laborem exercens qualifies the teaching of private ownership in relation to the common use of goods that all men, as children of God, are entitled to. The church "has always understood this right within the broader context of the right common to all to use the goods of the whole creation: the right to private property is subordinated to the right to common use, to the fact that goods are meant for everyone." Many of these concepts are again stressed in Centesimus annus, issued on the occasion of the 100th anniversary of Rerum novarum, which encompasses a critique of both socialism and unfettered capitalism. Another major milestone under John Paul II's papacy occurred in 2005, with the publication of the Compendium of the Social Doctrine of the Church, a work entrusted to the Pontifical Council for Justice and Peace. Pope Benedict XVI Pope Benedict XVI's 2009 encyclical Caritas in veritate added many additional perspectives to the social teaching tradition, including in particular relationships with the concepts of Charity and Truth, and introduced the idea of the need for a strong "World Political Authority" to deal with humanity's most pressing challenges and problems. This idea has proven to be controversial and difficult to accept, particularly by right-of-center U.S. Catholic thinkers who are generally suspicious, or even disdainful, of supranational and international organizations, such as the United Nations. The concept was further developed in a 2011 note issued by the Pontifical Council for Justice and Peace entitled "Towards reforming the International Financial and Monetary Systems in the context of World Political Authority". In Caritas in veritate, Benedict also lifted up Paul VI's social encyclical Populorum progressio, setting it as a new point of reference for Catholic social thought in the 21st century. Noted scholar Thomas D. Williams wrote that "by honoring Populorum progressio with the title of 'the Rerum novarum of the present age,' Benedict meant to elevate Populorum Progressio, conferring on it a paradigmatic status not dissimilar to that enjoyed by Rerum novarum throughout the twentieth century." Williams claims that the reason for this elevation is that Populorum progressio, "for all its real deficiencies, effected an important conceptual shift in Catholic