Socrates, one of the fathers of Western philosophy, claimed that the unexamined life isn't worth living, and most Buddhists would certainly agree with him. Because of the importance they place on logical reasoning and rational examination, many Buddhist traditions and schools have a strong philosophical flavor. Others place more emphasis on the direct, non-conceptual investigation and examination that take place during the practice of meditation. In either approach, direct personal experience based on self-awareness is considered key.
Although Buddhism emphasizes direct investigation and experience, it does put forth certain philosophical tenets that sketch out a basic understanding of human existence and serve as guidelines and inspirations for practice and study. Over the centuries, Buddhism actually grew into a variety of schools and traditions, each of which had its own more or less elaborate and distinct understanding of what Buddha taught. In addition to the discourses memorized during the founder's lifetime and recorded after his death, numerous other scriptures emerged many centuries later that were attributed to him.
Despite all its philosophical sophistication, however, Buddhism remains at heart an extremely practical religion. Buddha has often been called the Great Physician for good reason: He always avoided abstract speculation and made identifying the cause of human suffering and providing ways to eliminate it his chief concern. Likewise, the teachings (known as the dharma) he shared are known as powerful medicine to cure the deeper dissatisfaction that afflicts us all. Buddha's first and best-known teaching, the Four Noble Truths (suffering; cause of suffering; cessation of suffering; the path that leads to the cessation of suffering), outlines the cause of suffering and the means for eliminating it. All subsequent teachings merely expand and elaborate upon these fundamental truths.
At the core of all genuine dharma teachings is the understanding that suffering and dissatisfaction originate in the way your mind responds and reacts to life's circumstances — not in the raw facts of life. In particular, Buddhism teaches that your mind causes you suffering by attaching to permanence and constructing a separate self where in fact neither exists.
Reality is constantly changing; as the Greek philosopher Heraclitus said, you can't step into the same river twice. Success and failure, gain and loss, comfort and discomfort — they all come and go. And you have only limited control over the changes. But you can exert some control over (and ultimately clarify) your chattering, misguided mind, which distorts your perceptions, mightily resists the way things are, and causes you extraordinary stress and suffering in the process.
Happiness, Buddha once said, is actually quite simple: The secret is to want what you have and not want what you don't have. Simple though it may be, it's definitely not easy. Have you ever tried to rein in your restless and unruly mind, even for a moment? Have you ever tried to tame your anger or your jealousy, control your fear, or remain calm and undisturbed in the middle of life's inevitable ups and downs? If you have, you've no doubt discovered how difficult even the simplest self-control or self-awareness can be. To benefit from the medicine Buddha prescribed, you have to take it — which means, you have to put it into practice for yourself.