Well, it's a deliberate change that he makes later on in response to a feeling that people (not only critics, but admirers like Sartre) haven't understood his w

Well, it's a deliberate change that he makes later on in response to a feeling that people (not only critics, but admirers like Sartre) haven't understood his work. In "Letter on Humanism" he says of the relatively straightforward language of Being and Time: I have learned to see that these very terms were bound to lead immediately and inevitably into error. For the terms and the conceptual language corresponding to them were not rethought by readers from the matter particularly to be thought; rather, the matter was conceived according to the established terminology in its customary meaning. In short, he tried to say something new using all the old terms[1], and that allowed readers to assume something about the meaning of those terms rather than work it out for themselves. So, to get his point across, Heidegger starts looking for a new way of saying, one without shortcuts, one that forces readers to think things through. Did it work? In a sense. Of course it also ensured that a lot of people will never bother reading Heidegger. For me, I simply treated Heidegger as a foreign language and learned to speak it. Once you're over the hump, he's not wildly difficult, and the reward, I think, is not unlike what you get out of learning, say, a functional programming language. It gives you new eyes, rather than just showing you some new thing. 1. 'Term' is often used with a special meaning in Heidegger. From On the Way to Language (with a few bits omitted): "Everybody sees and hears words. They are; they can be like things, palpable to the senses. To offer a crude example, we only need to open a dictionary. It is full of printed things. Indeed, all kinds of things. Plenty of terms, and not a single word. Because a dictionary can neither grasp nor keep the word by which the terms become words and speak as words."