The three main types of secondary education in the United States have been provided by the Latin grammar school, the academy, and the public high school. The first of these was a colonial institution. It began in New England with the establishment in 1635 of the Boston Free Latin School. The curriculum consisted mainly of the classical languages, and the purpose of this kind of school was the preparation of boys for college, where most of them would be fitted for the ministry.
The academy began in the early 1750"s with Benjamin Franklin"s school in Philadelphia, which later became the University of Pennsylvania. It extended generally to about the middle nineth century, except in the southern states where the public high school was late in developing and where the academy continued to be a principal means of secondary education even after 1900. The academy was open to girls as well as to boys, and it provided a wider curriculum than what the Latin grammar school had furnished. It was designed not only as a preparation for college but also for practical life in commercial and business activities. Although its wide educational values are evident and are recognized as important contributions to secondary education in this country, the academy has never been considered a public institution as the public high school has come to be.
The public high school had its origin in Massachusetts in 1821 when the English Classical School was established in Boston. In 1827, the state enacted the first state wide public high school law in the United States. By 1840, there were perhaps a dozen public high schools in Massachusetts and many in other eastern states by 1850, they could also be found in many other states. Just as the curriculum of the academy grew out of that of the Latin grammar school, the curriculum of the public high school developed out of that of the academy. The public high school in the United States is a repudiation (推翻) of the aristocratic and selective principle of the European educational tradition. Since 1890, enrollments in secondary schools, mainly public high schools, have practically doubled in this country every ten years. It is implied but not stated in the passage that ______.