Today is a Buddhist holiday that commemorates the day that the historical Buddha, Shakyamuni or Siddhartha Gautauma, experienced enlightenment or, in other words, found that life boiled down to Four Noble Truths:
1. All beings are subject to suffering. No one escapes... suffering is universal.
2. The cause of suffering is Ignorance. And Ignorance of oneself is the greatest Ignorance.
3. Ignorance, the cause of suffering, can be overcome, and
4. The way to overcome Ignorance is the Eightfold Path.
From that point forward, he was referred to as the Buddha, the Enlightened One.