Introduction

After the failure of the Treatise, Hume rewrote its first book as this shorter and more readable work. He divides all human knowledge into two kinds: 'relations of ideas', like mathematics, which can be known by thought alone, and 'matters of fact', which can come only from experience. We believe that the sun will rise tomorrow and that fire will burn us on the basis of cause and effect; yet we never actually observe any 'necessary connection' between cause and effect; we only see one event follow another again and again, and by 'custom' expect it to do so again. The book contains the famous essay 'Of Miracles' and ends with the fierce words that a volume containing neither abstract reasoning about quantity nor experimental reasoning about matters of fact should be 'committed to the flames'. Kant said it was Hume who woke him from his 'dogmatic slumber'.