Plato's works are very readable. Since he was the father of philosophy, there was no technical vocabulary at the time. He wrote in the form of dialogues, so the prose is less dry than mere treatises. Aristotle is a little more difficult, but he is still very systematic and clear as long as you can pay attention. Mortimer Adler is one of the clearest and most common-sensical writers in philosophy. St. Thomas is not easy to read, but he is the essential Catholic philosopher. Popes, Church Councils, philosophers, and theologians have all sung his praises. The Bible (start with the New Testament if you haven’t already) and the Compendium to the Catechism of the Catholic Church (It’s the short version – or you can go for the Catechism itself if you are feeling ambitious). God Himself is truth, and philosophy is the path that leads to Truth.

Beauty is the splendor of truth. If we find something that is truly beautiful, then we know that we have found something true. Most of the time, new scientific theories meet with great resistance within the scientific community; it takes a long time for scientists to be convinced of new ideas. But in the case of Einstein’s theory of General Relativity, almost all scientists believed it as soon as they saw it. Even though there was little evidence for it at the time and it had not really been put to the test, most scientists knew that it was right because of its beauty.

Ethics is about the good life. The study of happiness and virtue helps us understand how we ought to spend our time and live life to the fullest. This topic provides us with an answer to the age-old question about the meaning of life. What most people mean when they ask about the meaning of life is, “What is my purpose?” The answer is to reach your fullest potential. Matthew Kelly has phrased it as: become the best version of yourself. The Church calls it the universal call to holiness and to become a saint. The Ancient and Medieval philosophers called it becoming virtuous and thriving. In the context of Catholicism where God Himself is the ultimate goal, they all mean the same thing. This might not seem very satisfying, but it is, and the evidence is the saints. They pursued holiness with abandon, and the joy practically drips off the pages of their writings and writings about them.

Happiness is one of the words that we use without giving a clear definition. So it is really easy to equivocate with that word (use the word in more than one sense). The types of happiness discussed in the first paragraph are types of happiness, but Plato, Aristotle, St. Augustine, St. Thomas Aquinas and many other wise people discuss a different type of happiness. You might be wondering why we are discussing happiness in a chapter about ethics, but the Ancients, the Medievals, and the Church all say that happiness is the main point in ethics. Only since the “enlightenment” (when everybody went on a diet) has ethics become about anything else. The classical idea of happiness was when a man reached his fullest potential and is thriving.

Due to man’s body-soul unity, we do not begin our lives knowing anything at all, but we are born with innate abilities. As we interact with the world, real objects impress themselves on our senses, and an image is formed in the intellect of those objects. Our intellect is then able to abstract the essences of things and their properties. For example, when I see a table, my senses perceive the table. My abstract intellect then takes the sense impression and abstracts those characteristics to form the idea of a table. As I see more tables, this idea is refined. Our mind, then, is able to recognize those same essences in other things and analyze those abstract concepts derived from our experience with the world. As we discover new things, our minds are able to think about how those new things are different from the other things we know. When I see a tree, I know that it is not a table because it doesn’t fit with my idea of table. And as we discover different things in the same class, like learning that there are different types of tables, our mind is able to tell us how these are the same and yet different from each other. Lab tables, dinner tables, and coffee tables are all tables, but they are not the same type of table. Telling the difference between things is an important part of learning and knowing. This theory of knowledge fits perfectly with the body-soul unity of man and the fact that we interact with real objects, and so the name of this theory is realism.

The vast majority of people would find it horrifying to never be able to interact with people ever again. It seems that we were built for each other. As Aristotle said, man is a social animal by nature. It is part of the essence of man to live with other people and for men to organize themselves into societies. It is through this type of observation and reasoning that we can figure out the nature of this thing called a human being.

Picture in your mind the cave. People are lined up in rows, all facing forward. Above and behind them there is a light that produces an image on a large wall in front of them. What does this sound like? A movie theater? And how often are we convinced that the world in the movies is real life and that our own lives are just a boring copy of the movie world? That the fame, violence, vengeance, lust, greed, fancy cars, big houses, expensive stuff and excitement are what life is all about? Philosophy calls out and brings your attention back to reality, back to the beauty and goodness of the world all around you.

I was once asked what my favorite topic in philosophy is. It took me a second to think through the various topics, but as soon as I thought of it, I knew it: God. This was a surprising answer to the person who asked the question, because God is always thought of as a strictly religious entity. But philosophy can also give us a lot of information about God, and no subject is more beautiful. We call this natural theology because we are finding out what we can about God using only our natural resources. It is very difficult and very abstract because when we think about God we are thinking about Someone who we cannot fully grasp. Augustine once said, “If you understand it, it is not God.” In other words, if you have some accurate, neat little picture in your mind of God, then that picture is wrong.

The basic and most fundamental law of logic: the law of non-contradiction, which states that a thing cannot be and not be in the same way and at the same time. After all, I could look at a piece of paper folded like a chair and say, “That chair is not a chair,” but what I really mean is that the piece of paper shaped like a chair is not a chair that you can sit in. The sentence, “that chair is not a chair,” uses the word “chair” in two different ways. And since we have already made sense of the way things change, then we know that a piece of wood can be a tree tomorrow and then a table the next day. It is not a contradiction to point to a collection of matter and say that it was not a statue a month ago and it is a statue today. “Statue” and “not-statue” refer to two different times. So, the full law of non-contradiction says that a thing cannot be and not be in the same way and at the same time.

This study of the nature of existence is called Metaphysics. It is the most foundational topic in philosophy because anything else that we can talk about is something that exists, and it is sometimes called “first philosophy.” Metaphysics gets its name because the book that Aristotle wrote on this topic came after his book about physics. Meta- in Greek means after. So, this book was called the “after-physics” or “Metaphysics.”