I. "Most thought-provoking" The phrase suggests that there is a specific and yet universal issue that is most thought-provoking. This suggestion amounts to the contention, in a contemporary argot, that there is an objective value-structure built into thinking. That which is most thought-provoking is not a matter of subjective evaluation. That which is most thought-provoking is not something for us to determine but rather for us to discover. To think, Heidegger claims, is to respond to what most demands our thinking, and that which most demands our thinking is a universal matter. Heidegger's contention is thus analogous to Augustine's contention about happiness in The Confessions. Augustine's key thesis is that happiness is a matter of properly ranking desires, and that there is an objective ranking of desires. One cannot be happy in the fullest sense if one's desire-set does not mirror the objective valuation of desires. Augustine thus concludes that happiness is a matter of ranking the desires for truth and God--both being eternal, secure, and nonexclusive--at the top of the hierarchy. In like manner Heidegger is advancing the thesis that one cannot think in the fullest sense if one does not think about that which most calls for thinking. Thinking involves the ranking of items in terms of their thought-worthiness, and for Heidegger that means locating the Being of the thinker (and thus Being itself--see Lecture VII, p. 79) at the top of the hierarchy. Was Heisst Denken?, as I noted above, could be translated as either What Is Called Thinking? or as What Calls For Thinking?. This puzzling choice of title can now be resolved, for the foregoing shows not only that Heidegger intends the ambiguity but also the reason why. Heidegger's point is that one cannot properly address the question What Is Called Thinking? without answering the question What Calls For thinking? This distinction between the two questions and the priority given to the latter over the former I take to be Heidegger's most valuable contribution to discussions of thinking or rationality. One is not thinking if one does not rank objects of thought in terms of thought-worthiness. This point flies in the face of many contemporary accounts of rationality, for they suggest that one can be thinking well as long as one is following the right method. What one thinks about plays no normative role on such "ratio-inspired" accounts (see below for the contrast to legein-inspired models); indeed, critical thinking has come to mean critical qua method-following thinking instead of critical qua essential thinking. Heidegger's point is that such means-end accounts involve and indeed propagate a distortion; a life spent rationally researching the history of administrative memos is not a thoughtful life. (7) In rationally pursuing anything and everything we are not thinking. Being calls for thinking, and it is the peculiar task of the philosopher to articulate this most intimate and yet universal issue. The idea that this (or anything) should be most thought-provoking does not sit well with many contemporary philosophers, but it is precisely the failure of philosophers to take to heart the importance of thought-worthiness that leads Heidegger to take a dim view of much of philosophy. On the other hand, though, he does claim that philosophers are "the thinkers par excellence". (8) What justifies this self-adulation? The reason is that the issue of thinking is one that falls squarely within the province of philosophy. (9) The philosopher differs from the chess player, biologist, and politician in that the philosopher's calling is to think about thinking as such. Moreover, to think philosophically about thinking, for Heidegger, is to come to a confrontation with a mode of existing--"being-thoughtful"--and thereby with Being. The idea of thought-worthiness serves to unify large chunks of text. Heidegger observes that this idea rings alien to modern ears, and thus goes on to discuss the modern age--this thought-provoking time in which we are still not thinking--via a philosopher who has his finger on the pulse of the present age--Nietzsche. The idea of thought-worthiness also leads Heidegger to discuss a past time in which the ranking of issues in terms of thought-worthiness was manifest in the experience of thinking. This age was philosophy in the age of the Greeks, and it is a reason why Heidegger devotes the last lectures in Part Two to a reflection on Parmenidean Fragment 6.