=The Secondary System.=--The main types of secondary schools in Prussia are the _Gymnasien_ (see p. 114), with the classic languages as the main feature of their course, and the _Realschulen_, or real-schools (see p. 176), characterized by larger amounts of the modern languages, mathematics, and the natural sciences. For more than a century after the first real-school was opened in Berlin by Hecker (1747), this type of institution had only six years in its course, and was considered inferior to the gymnasium. By the ministerial decree of 1859, however, two classes of real-schools were recognized, and those of the first class had a course of nine years, and included Latin, but not Greek. They were given full standing as secondary schools, and graduates were granted admission to the universities, except for the study of theology, medicine, or law. The course of the second class of these institutions contained no Latin, and was but six years in length. In 1882 the compromise character of the course of the first class of institutions led to their being designated as _Realgymnasien_, while the second class in some instances had their work extended to nine years and became known as _Oberrealschulen_. The graduates were then allowed the privilege of studying at the universities in mathematics and the natural sciences. Since 1901 the university courses have been thrown open to graduates of any of the three types of secondary schools, except that, to be eligible for theology, one must have completed the course of a gymnasium, and for medicine, the course of a real-gymnasium at least. Besides these schools that have been mentioned, in rural districts where a complete course cannot be maintained, there are often secondary institutions that do not carry the student more than six years. These are known, according to the curriculum, as _Progymnasien_, _Realprogymnasien_, and _Realschulen_. The first two classes are far less common than institutions with the longer course of the same character, but the _Realschulen_ are nearly twice as numerous as the _Oberrealschulen_. [Sidenote: _Reformschulen_;] [Sidenote: the _Vorschule_.]