He had become the Buddha, which means teacher, and he taught the Four Noble Truths.

他已经成佛，也就是老师，他教导了四圣谛。

In terms of Buddha's specific philosophical  ideas, his core principles are contained in what he termed The Four Noble Truths.

就佛陀的具体哲学思想而言，他的核心原则包含在他所谓的四圣谛中。

One of the most famous of Ashoka's pillars is  at Sarnath, thought to be the site of Buddha's first sermon concerning the four noble truths.

阿育王最著名的柱子之一位于鹿野苑，被认为是佛陀第一次讲授四圣谛的地方。

At the heart of my teachings is the concept of Four Noble Truths: the truth of suffering, the origin of suffering, the cessation of suffering, and the path to the cessation of suffering.

佛陀：我教义的核心是四圣谛的概念：苦谛、苦集、苦灭、苦灭道。