Under that tree, Siddhartha Gautama attained supreme Enlightenment. Thereafter he became known as the Buddha, the Awakened One. He is referred to also by the names Sakyamuni Buddha and Gautama Buddha.
In his first sermon, the Buddha taught the Four Noble Truths: 1.) Life is suffering 2.) Suffering is caused by ignorance 3.) Overcoming ignorance transcends suffering 4.) The life that transcends suffering reflects the Eightfold Noble Path: correct views, thoughts, conduct, speech, livelihood, effort, mindfulness, and meditation.
He realized that life’s great events are its greatest suffering: birth, sickness, old age and death. Suffering also takes other forms: not getting what one wants, separation from loved ones, anger, delusion, greed and the incessant craving for wealth, status, possessions and love.
The Buddha taught that life is transitory and impermanent. No matter how hard we try to hold on to our health, we become ill, no matter how hard we try to hold on to our youth, we grow old, and no matter how hard we try to hold on to people we love, death brings separation and ultimately our own demise.
The Buddha saw that we suffer because we don’t see life clearly. Rather, we live in a world clouded by our passions and ignorance, driven by a desire to please this “self” of ours. We divide the world into yours and mine, good and bad, happiness and sadness, life and death, with this self at center. We fail to see the Oneness of life.