In Jim Morrison's "Letters from Joe," he explores the themes of knowledge and the unknown, emphasizing the complexities of understanding life. He suggests that while there are certainties we can grasp, there are also vast uncertainties that remain elusive. The idea of doors symbolizes the countless opportunities and experiences that lie between the known and the unknown, inviting exploration and contemplation.

Morrison's quote, "There are things known and there are things unknown and in between are the doors," highlights the significance of curiosity and the pursuit of knowledge. It suggests that growth and discovery occur when we venture beyond our comfort zones into the realms of the unknown. Ultimately, it serves as a reminder of the importance of seeking out these 'doors' to enrich our understanding of existence.