In the instruction in public schools care shall be taken not to hurt the feelings of those of differing opinion. Civics and manual training are included in the school curriculum. Every pupil receives a copy of the Constitution on completing the obligatory course of study. The common school system, including university extension work, shall be cherished by the Commonwealth, States and municipalities. ARTICLE 149 Religious instruction is included in the regular school curriculum, except in the nonsectarian (secular) schools. The imparting of religious instruction is regulated by the school laws. Religious instruction is imparted in accordance with the principles of the religious society concerned, without prejudice to the right of supervision of the state. The imparting of religious instruction and the use of ecclesiastical ceremonies is optional with the teachers, and the participation of the pupils in religious studies, and in ecclesiastical ceremonies and festivities is left to the decision of those who have the right to control the religious education of the child. The theological faculties in the universities will be continued. ARTICLE 150 The artistic, historical and natural monuments and scenery enjoy the protection and care of the state. The prevention of the removal of German art treasures from the country is a function of the Commonwealth. _SECTION V_ ECONOMIC LIFE ARTICLE 151 The regulation of economic life must conform to the principles of justice, with the object of assuring humane conditions of life for all. Within these limits the economic liberty of the individual shall be protected. Legal compulsion is permissible only for safeguarding threatened rights or in the service of predominant requirements of the common welfare. The freedom of trade and industry is guaranteed in accordance with the national laws. ARTICLE 152 Freedom of contract prevails in economic relations in accordance with the laws. Usury is forbidden. Legal practices which conflict with good morals are void. ARTICLE 153 The right of private property is guaranteed by the Constitution. Its nature and limits are defined by law. Expropriation may be proceeded with only for the benefit of the community and by due process of law. There shall be just compensation in so far as is not otherwise provided by national law. If there is a dispute over the amount of the compensation, there shall be a right of appeal to the ordinary courts, in so far as not otherwise provided by national law. The property of the States, municipalities, and associations of public utility may be taken by the Commonwealth only upon payment of compensation. Property-rights imply property-duties. Exercise thereof shall at the same time serve the general welfare.