The mountain talk

The Sermon on the Mount, one of the most important parts of the New Testament with the eight sentences about happiness, Our Father or the Golden Rule, is the essence and essential summary of the teaching of Jesus Christ. What did Jesus say and why did he say his speech had such a huge impact on his early listeners (and us)? I think when we re-read the text now, we can get a lot of recognition that may have slipped before our eyes so far.