Among the many intellectual accomplishments for which Jaakko Hintikka is recognized is his pioneering work in epistemic logic. Although epistemic logic was studied somewhat in the Middle Ages the real breakthroughs are to be found in the work of von Wright [59] and most notably Hintikka's seminal book Knowledge and Belief: An Introduction to the Logic of the Two Notions from 1962 [24]. There has hardly been an article or book published on the logic of knowledge and belief since that has not made reference to this exquisite treatise.