Metaphysics - Aristotle
First, I want to thank LibriVox for making this book freely available in an audio edition.
This is the only 3 star book where I would recommend it to everyone. My start of reading primary philosophy started with Heidegger, that led me to Hegel and then Kant. There's no doubt I should have suffered through this book first, because those authors rely on Aristotle in many ways and not just to tear him apart but to add to how Aristotle approached the topic of metaphysics.
I've learned to no longer trust commentaries of the great works of philosophy. The summaries just seem to get it wrong. One must go to the primary source to understand what was really said. Most of the time people comment on the Metaphysics they emphasis the four causes (form, matter, efficiency, and final cause). While they are right they are in the book, they are missing the heart of the matter.
Metaphysics is really defined by this book. Ontology, the science of being, the what is there, or the what is the furniture that makes up the room and what is that furniture really made up of are discussed in this book. Also, the foundation, the primary structure, the first causes of the world is looked at. Aristotle values both the empirical and the rational, the world of the physical and the abstract. Also, the nature of science is analyzed.
Aristotle speaks logic. He beats into the reader the meaning of mutually exclusive (something has to either be or not be at the same time and place) and contradiction (something can't be and not be at the same time and place). At his best, Aristotle puts reality back in to the dialectics. From Heraclitus' a person can't cross the river because they and the river are always changing, or Parmenides change is impossible because there is no such thing as the void (don't completely dismiss that because Einstein's block universe leads to that too). Aristotle uses his logic to demolish those beliefs.
I've tried reading it before but never got out of Book 1. I now know why. Aristotle is verbose in his prose. The substance of the universe are not numbers. It only took me one one sentence to dismiss that notion. It takes Aristotle all of book 13 to say that with multiple chapters and what seems like run on sentences before he lays out his excruciating arguments.
I hate recommending this book because it is painfully written, but it has real insights which are painfully and slowly drawn out, and it's clear that this book has influenced many later day philosophers who I have recently read. (Kant systematically destroys most of Aristotle's conclusion, Heidegger obviously worshiped the occurentness (a Dreyfus neologism) of Aristotle, and Hegel follows Aristotle's soul, identity, and essence (to me, the most dangerous concept in science!).