Yasa, a wealthy young man, experiences profound revulsion at his life of sensual pleasure, exclaiming "Oh, what affliction!" and leaves home, encountering the Bhagavā (Buddha). The Buddha teaches Yasa a gradual discourse followed by the Four Noble Truths, leading Yasa to attain the "dust-free, stainless `dhammacakkhu` (insight into the Dhamma)" and, after his father also hears the Dhamma, full liberation as an Arahant and ordination as a bhikkhu. Yasa's father, initially searching for him, is also taught by the Buddha, attains the `dhammacakkhu`, and becomes the first lay follower; Yasa's mother and former wife similarly become the first laywomen followers. Inspired by Yasa, his four closest friends and later about fifty more also seek out the Buddha, receive the same progressive instruction, attain the `dhammacakkhu`, are ordained, and achieve Arahantship, significantly expanding the early Saṅgha.
