Not my first discourse, I hasten to add, but the Buddha’s first discourse.
That seems like an appropriate place to start. If you are reading this thread then I assume that you wish to know more about the teaching of the Buddha. I will be do my best to reply to any questions that you may have, as long as they are respectful and sincere.
The bodhisatta, Prince Siddhattha Gotama, renounced his palace at the age of 29 after seeing four signs: an old man, a sick man, a dead man, and a monk. Seeing that all living beings were trapped by old age, sickness, and death, he resolved to find an escape from this predicament. His noble quest began with the practice of self-mortification because it was believed at the time to be the way to liberation. He practised with five other ascetics as his companions. After six years of strenuous austerities, he realised that this was not the right path, and resumed taking adequate food and rest. Because of this, his five companions thought he had given up the quest, so they left him.
After regaining his strength and health the bodhisatta meditated the whole night and discovered the path leading to enlightnement. By the morning he had eradicated all craving and ignorance, and he gained Buddhahood with the rising of the dawn. Reflecting on the Dhamma that he had realised, he was at first disinclined to teach it, as it went against the current of human desires, and was difficult to understand. Nevertheless, he reasoned that some “with little dust in their eyes” would understand it, so he resolved to teach it.
Realising that his two former meditation teachers had already passed away, he went to Saranath to teach it to the five ascetics who had been his companions in the quest for liberation. When he told them that he had found liberation, at first they did not believe him, because they thought he had given up the path of striving. However, by reminding them of his lifelong honesty, he won them around and they agreed to listen to him. So he gave his first discourse, which is called the Dhammacakkappavattana Sutta – the setting in motion of the wheel of the truth.
This first discourse deals with the Middle Way, and the Four Noble Truths including the Eightfold Noble Path. It is very concise. By the end of the discourse only one of the five ascetics, Kondañña, understood it properly and realised nibbana, the other four had to practise meditation as instructed by the Buddha for some time before realising nibbana. Because he was so quick to understand this concise discourse, Kondañña became known as “Kondañña the Wise.”
The Middle Way
The Buddha began by stating that the way to liberation was the middle way, avoiding the two extremes of sensual indulgence and self-mortification. This middle way comprised eight factors: right view, right thought, right speech, right action, right livelihood, right effort, right mindfulness, and right concentration.
He didn’t explain it in detail, he just stated it in brief.
The Four Noble Truths
Then he stated the Four Noble Truths that he had realised:
1. The truth of suffering (dukkha): birth is suffering, aging is suffering, sickness is suffering, death is suffering, association with the unloved is suffering, separation from the loved is suffering, not getting what one wants is suffering, in brief the five aggregates of attachment are suffering.
2. The truth of the cause of suffering is the craving that causes repeated becoming, and takes delight now here now there, namely sensual craving, craving for existence, and craving for non-existence.
3. The truth of the cessation of suffering is the complete cessation and abandonment of this craving, and liberation from it without any remainder.
4. The truth of the way to attain the end of suffering, which is the noble eightfold path: right view, right thought, right speech, right action, right livelihood, right effort, right mindfulness, and right concentration.
That, very briefly, is the essence of the first discourse. The Buddha went on to explain that until he had thoroughly realised these four noble truths he did not claim to be fully enlightened. Merely knowing these four truths intellectually is not enough, we have to thoroughly understand them to gain liberation.