Here's why:
* Introduces the main idea: The introductory paragraph sets the stage and provides context for the essay.
* Leads to the argument: The thesis sentence, placed at the end, acts as a bridge, smoothly transitioning from the introduction to the main argument of the essay.
* Clear focus: Ending with the thesis sentence emphasizes the central claim and gives the reader a clear understanding of what the essay will discuss.
While not a hard and fast rule, this structure helps create a strong, focused introduction.