As you probably noticed from the selections in Kuhn's ch. 3, Aristotle is not easy to read, so 25 pages of him may take longer than 50 pages of Kuhn. There are two things to remember if you find yourself bogging down. First, don't assume that you need to understand everything in order to get the main points he makes: even people who are very familiar with his thought find the text very obscure in places. Secondly, something that can be frustrating when you understand him can help when you are lost: the text often changes topics quite abruptly (so being lost in on paragraph doesn't mean you won't be able to follow the next one).

Although I'll encourage you to try to read all the selections Matthews includes, you are unlikely to have time to really study them all, so I'll suggest a few to focus on.

• Physics, bk. 2, chs. 2-3 (pp. 10-15). The first of these has something to say about the relation between mathematics and the natural sciences while the second introduces Aristotle's four causes, which are at the heart of his view of explanations (including scientific explanations). The second chapter will also provide some help with the distinction between form and matter that he uses in the first.
• Physics, bk. 4, ch. 8 (pp. 15-19). Aristotle here argues against the possibility of a vacuum, and you've already seen the importance of that for Aristotelian cosmology. Some of his arguments are interesting for other reasons because they give some insight into what might be called his laws of motion.
• Physics, bk. 7, ch. 5 (pp. 25-26). This has more about the laws governing motion.
• Posterior Analytics, bk. 1, chs. 1-2, 13 (pp. 26-32). The second of these three chapters is probably the most important but all can help in understanding Aristotle's views of the nature of scientific explanation and the organization and foundations of scientific knowledge.

Next in importance after these is the first selection from the Physics, in which Aristotle discusses the meaning of the term nature. The remaining selections concern the idea of a first mover. That idea is important in Aristotle's cosmology but it was less important than other aspects of his cosmological views for the course of the Scientific Revolution.