David Hume 
A Treatise of Human Nature [EPUB ebook] 

"A Treatise of Human Nature" by David Hume, published in the 18th century, is a seminal work in philosophy. Hume's empiricist and skeptical approach challenges traditional beliefs, focusing on the nature of human understanding, causality, and moral philosophy. He argues that all ideas originate from sense experience, critiquing the notion of causality as a mere habit of thought. In terms of morality, Hume posits that moral distinctions stem from sentiment rather than reason, an idea that has influenced ethical philosophy. This influential treatise has significantly shaped philosophical discourse, particularly in epistemology, metaphysics, and ethics, and remains a cornerstone of modern philosophical thought.