The philosopher Arthur Schopenhauer was no enthusiast for sleep or dreams. “Each day is a little life,” he wrote, “every waking and rising a little birth, every fresh morning a little youth, every going to rest and sleep a little death.” In the dark hours of night, Schopenhauer thought, people tended to lose themselves. Dangers lurked in the shadows; reason and vision were obscured, good judgment made impossible. Night, sleep and dreams – these were the primary enemies of the individual, who in daylight hours remained in supreme control of his mental faculties. Schopenhauer’s lament points to the key to dreaming: loss of control over mental functioning and the opening up of a different cognitive environment or reality, the dreamworld. The transition from waking consciousness into the dreamworld can be a jarring transformation. Here spatial, temporal, sensual and emotive rules are either reformed or discarded. Such a shift in reality can produce feelings of fear, disorientation, confusion, or perhaps liberation or ecstasy.  The universality and intensity of the dream experience have made the dream fertile ground for a diverse range of intellectual and artistic explorations since ancient times. This work on the nature of dreams presents a sampling of this enduring inquiry.  The goal of this work is to usher the reader across the threshold of sleep and into a broad array of dreamworlds, ones separated from each other by decades, centuries and millennia. The work – fractured and partial as an oneiric vision – is meant as a starting point for inquiry and analysis into the eternal and collective contemplation of the dream.