that all citizens have dignified work, education and healthcare." He explicitly affirmed "the right of states" to intervene in the economy to promote "the common good". He wrote: Francis has warned about the "idolatry of money" and wrote: In his second encyclical, Laudato si', the pope lays forth a "biting critique of consumerism and irresponsible development with a plea for swift and unified global action" to combat environmental degradation and climate change. With respect to climate change, some critics have argued that Francis is departing from the positions of his predecessors. Daniel Schwindt observed that "some writers seem to suggest (as is common among persons who've never taken the time to read the encyclicals themselves), that Pope Francis' Laudato Si represents some new venture on the part of the Church—a departure from its customary range of subject matter." But, Schwindt argues, his attitude toward climate change is a precise continuation of the attitude of his immediate predecessor. Pope Benedict XVI once wrote: Francis' apostolic exhortation Gaudete et exsultate emphasized the universal call to perfection of charity, which is based on "service of your brothers and sisters" (No. 14) and on the entirety of the Church's social teaching tradition. Principles Every commentator has his or her own list of key principles and documents, and there is no official 'canon' of principles or documents. Human dignity Human dignity is one principle of Catholic social thought. According to the Catechism of the Catholic Church, "Being in the image of God, the human individual possesses the dignity of a person, who is not just something, but someone. He is capable of self-knowledge, of self-possession facts, and of freely giving himself and entering into communion with other persons. And he is called by grace to a covenant with his Creator, to offer him a response of faith and love that no other creature can give." Subsidiarity The origins of subsidiarity as a concept of Catholic social thought lie with Wilhelm Emmanuel von Ketteler, who served as Bishop of Mainz in the mid- to late 19th century. It is most well-known, however, from its subsequent incorporation into Pope Pius XI's encyclical Quadragesimo anno. This encyclical's formulation of subsidiarity is the touchstone from which further interpretations tend to depart: "Just as it is gravely wrong to take from individuals what they can accomplish by their own initiative and industry and give it to the community, so also