According to Siddhartha Gautama (the original Buddha), these four truths, once realized, will lead one to enlightenment.
  1. Suffering exists.
  2. Suffering is caused by attachment to craving and desire.
  3. Suffering ceases when its cause (see #2) ceases.
  4. Freedom from suffering is possible by detaching oneself from craving and desire.
The Buddha-recommended method of performing this incredible feat of will (#4) was to follow the Eightfold Noble Path.