The god associated with boundaries and transitions in mythology is often represented by Hermes in Greek mythology. As the messenger god, he oversees travel, commerce, and communication, embodying the passage between different realms. Hermes is also known as the guide for souls to the underworld, reinforcing themes of crossing thresholds and transformation. His role emphasizes the importance of navigating life's changes and challenges, reminding individuals of the fluidity of existence and the potential for new beginnings at every transitional moment.