The Dutch contributed in several ways to the development of classical liberalism and many of these contributions are still visible in current Dutch society. Main examples are found in the development of capitalism, including free trade and stable institutions, and pleas for freedom of conscience and other personal liberties. Some of these ideas have roots in the writings of great Dutch writers, such as Erasmus, Grotius, Spinoza, Pieter and Johan de la Court, or Bernard Mandeville. Into the 18th century, however, Dutch classical liberalism lost its vitality and ascendance. From the mid-19th century onwards, social liberalism started to take over as the dominant liberal variant in Dutch politics. Generally, classical liberal influence waned, persisting with the odd exception now and then, for example through the work of thinker-politician Frits Bolkestein in the 1990s.