The sermon of Al-Gharra is one of the long sermons of Imam Ali (pbuh) which has been considered by commentators and men of letters throughout history due to its eloquence and rhetoric and its excellent content. One of the most important questions in relation to this sermon is the discovery of the main subject and the purpose of Imam Ali in expressing these matters. Studies show that each of the commentators has considered a specific topic for this sermon and has explained it, including: piety, attributes of God, The story of man, avoiding worldliness, describing the resurrection, warning of the resurrection and so on. In this research, an attempt has been made to use the content analysis method and extract important categories of the text, the geometric structure of the sermon is explained and finally the main subject of the sermon is identified. The findings show that Imam Ali in this enlightening and eloquent speech sought to draw a roadmap for the salvation of human beings. For this reason, he first introduces man and his talents, then reports his present (worldly life) and future (hereafter life) status, and in this way, he has informed man of the opportunities and threats ahead, and finally the main solution of salvation, ie piety has introduced and explained its fruits. The pattern obtained from the analysis of the content of the categories of this sermon can depict the solution of salvation and happiness of human beings in the world.