because as says Aristotle
philosophy is not for young men
their Katholou can not be sufficiently derived from
their generalities cannot be born from a sufficient phalanx
lord of his work and master of utterance
who turneth his word in its season and shapes it (Ezra Pound)
Your knowledge as a scholar falls back on your knowledge of concrete particulars about which you are the authority. There are things that your peers know today only because one of them (perhaps you) first discovered them. In the social sciences, we are often talking about what you learn about a particular domain of fact from your data. Before you make your results available to your peers, only you know about these facts (the particular organization that you have studied, for example). Only you know what your interview subjects said. Only you know what was going on while you were observing them.
This kind of knowledge constitutes about half of a journal article, especially in the results section and the methods section. After all, just as you know best what you saw (i.e., your results), you know best what you did (i.e., your method). Before you tell the reader these things, the reader has no chance of knowing. So you speak here with a particular kind of authority.
The exercise, then, is to spend four minutes writing some sentences that only you (and nobody else) knows are true. Then pick one of these sentences and re-write it for four minutes. Then take a break. Again, let me stress that once you're comfortable with the basic motion of writing down facts about which you are the authority, you can do the exercise however you like. You can repeat it. Or you can go back to one of the other exercises. Or you can start writing a paragraph elaborating and supporting the sentence (for the remaining twenty minutes of the writing session).
What you are giving yourself here is simply an opportunity to "go through the motions" of writing factual prose without having to dig deep for the "strength" to support it. You pick something you know well, something you can write about comfortably, and then you simply write a sentence you know to be true. In this case, it's even a sentence that no one is going to be in a position to critique the content of (they haven't seen what you've seen, done what you've done). As with the other exercises, it's like moving your arm without lifting anything. Just concentrate on the motion of your prose.