David Hume 
A Treatise of Human Nature [EPUB ebook] 

My design in the present work is sufficiently explained in the Introduction. The reader must only observe, that all the subjects I have there planned out to myself, are not treated of in these two volumes. The subjects of the Understanding and Passions make a compleat chain of reasoning by themselves; and I was willing to take advantage of this natural division, in order to try the taste of the public. If I have the good fortune to meet with success, I shall proceed to the examination of Morals, Politics, and Criticism; which will compleat this Treatise of Human Nature. The approbation of the public I consider as the greatest reward of my labours; but am determined to regard its judgment, whatever it be, as my best instruction.