Final answer:
Paulo Coelho used the prologue in 'The Alchemist' to introduce the concept of a Personal Legend and set the tone for the story.
Step-by-step explanation:
Paulo Coelho used the prologue in 'The Alchemist' to provide context and set the tone for the story. The prologue introduces the readers to the idea of a Personal Legend - a purpose or destiny that each person has. It also foreshadows some of the key themes and symbols that will be explored throughout the book, such as the pursuit of dreams, the importance of following one's heart, and the search for meaning and fulfillment.