David Hume: Father of Scientific Liberalism

In Appendix 1 of his book Liberalism, Ludwig von Mises wrote:

Liberal ideas are already to be found in the works of many of the earlier writers. The great English and Scotch thinkers of the eighteenth and the beginning of the nineteenth century were the first to formulate these ideas into a system.

When fragmentary insights are integrated and systemetized, that is the mark of a science.  Mises then offers a list of these "scientific liberals", and the works by them which one should read.  The earliest work on his list is: David Hume, Essays Moral, Political, and Literary (1741 and 1742).