 Arnauld’s account of clarity and distinctness, obscurity and confusion of ideas can be found in the First Part, Chapter 9, of the Logic. The discussion proceeds by way of examples, rather than general definitions, but it can be summarized as follows: The basic properties of ideas are clarity and confusion. Clarity of ideas is the same as vividness, and this is a matter of degree; the opposite of clarity is obscurity. Confusion of ideas results when a number of ideas are connected by false judgments, and confusion produces obscurity. Opposite to confusedness of ideas is distinctness. Arnauld and Nicole apply these distinctions to the idea of pain: