That both I and you have had to travel and trudge through
this long round is owing to our not discovering,
not penetrating four truths. What four?
They are: The Noble Truth of Suffering,
The Noble Truth of the Origin of Suffering,
The Noble Truth of the Cessation of Suffering,
and the Noble Truth of the Way
Leading to the Cessation of Suffering.
Digha Nikaya, Sutta 16
The Dhammacakkappavattana Sutta, the Buddha’s teaching on the Four Noble Truths, has been the main reference that I have used for my practice over the years. It is the teaching we used in our monastery in Thailand. The Theravada school of Buddhism regards this sutta as the quintessence of the teaching of the Buddha. This one sutta contains all that is necessary for understanding Dhamma and for enlightenment.
Though the Dhammacakkappavattana Sutta is considered to be the first sermon the Buddha gave after his enlightenment, I sometimes like to think that he gave his first sermon when he met an ascetic on the way to Varanasi. After his enlightenment in Bodh Gaya, the Buddha thought: “This is such a subtle teaching. I cannot possibly convey in words what I have discovered[…]”
Excerpt From: Ajahn Sumedho. “The Four Noble Truths.”