Why does the captain tell sefano about the colomber?

The captain tells Stefano about the colomber to warn him of the danger that the mythical creature represents. The colomber is said to pursue those who are marked for a life of fear and suffering, and the captain aims to prepare Stefano for the challenges ahead. By sharing this tale, the captain seeks to impart wisdom about facing one's fears and the consequences of evading one's destiny. Ultimately, it serves as a cautionary tale about the importance of courage and acceptance in life.