St. Thomas is undoubtedly the greatest spokesman of Aristotle ever. In this commentary, he achieved something apparently simple but almost humanly impossible: expressing Aristotelian physics in intelligible words. Aristotle, on the other hand, only made a few half-hearted attempts, and more or less failed. On top of that, he also provides us with some mediaeval debates on Aristotelian themes, notably involving arguments from his contemporary Averroes. Thomas can be very wordy from time to time, but because his narrative is structured in such a clear way, those with good background knowledge of Aristotelian physics can skim through without much difficulty.