The principle of a universally accessible system of education has top priority, and in fact the near-universal nature of education in Bulgaria has brought about almost complete literacy. Whereas before 1944 many Bulgarians had never attended school, in mid-1973 almost every Bulgarian was able to attend some form of school. In some areas of the educational system, particularly in institutions of higher education, the number of students has increased as much as eightfold. Another principle of communist education in Bulgaria is the concept of socially useful work, which must be performed by all students at all levels of education. The principle of work in education is initiated at the very lowest levels of the system; it progresses into increasingly longer periods as the student advances in the school system. In the higher grades, students work for significant periods of time in agriculture, industry, and construction. In the higher levels of education the student must sign a document that obligates him to accept a working assignment, which should be related to his field of specialization, for a period of three to five years. Another facet of the system is the eradication of old values and their replacement with new socialist values (see ch. 4). One of the first tasks of Bulgarian educators was to eliminate religious teachings and practices in the schools. Religion, as a subject, was eliminated in the early years as was the history of the Bulgarian Orthodox Church. Students are taught that atheism is both reasonable and scientific; religion is dismissed as a relic of a superstitious and undesirable past. By the same token, students are indoctrinated strongly by teachers, directors of extracurricular activities, and colleagues to revere and swear allegiance to the government. Another guiding principle of the educational system in Bulgaria, which was initiated at the time of the takeover and still obtained to some degree in 1973, is the concept that sons and daughters of the worker and peasant classes should be favored in terms of their preference of access to education, particularly at the higher levels. This policy was clearly motivated by a desire to compensate for the exclusion of this class from such institutions in the past. In the early communist years institutions of higher education charged tuition, but children of the worker-peasant classes were exempted. By 1954 this class constituted 20 percent of the higher education population, a figure that by 1970 had risen to 78 percent. In 1973 the government was still maintaining a preferential clause for these students in higher education and reserved 10 percent of the places in such institutions for them.