The essence of human nature is intrinsic and unchanging. Human nature tends towards disorder. Societal institutions exist to prevent the tendency towards disorder.
Societal institutions exist to work with human nature to maintain order.
Human nature is learned and mutable. Human nature tends neither towards order nor disorder. Societal institutions exist to shape human nature to create order. Modern liberalism shares little in common with the classical liberalism of Thomas Jefferson, James Madison, et al. Classical liberalism appreciated human nature for what it was and created a constitution and adopted a rule of law to work within that understanding of human nature.