Dreams could be divided into three categories: divine, supernatural, and natural; and they were thought to foretell the future. Many were convinced that if they could unlock the meaning of dreams, they could know the future.
Wilhelm Scribonius defines a dream as “an inward act of the mind” while the body is sleeping. The soul creates dreams from the spirits of the brain, and the most pleasant dreams come as morning approaches, when the spirits are most pure.
William Vaughan writes about both sleep and dreams in his treatise on personal health. He warns of the dangers of sleeping at noon and observes that dreams could either be a remembrance of the past or “significants of things to come.”
Thomas Cooper argues that some dreams are natural and might inform us “of the sinnes of the heart,” since what we think or do during the day returns as dreams at night. But he is most concerned with dreams that came from God—moving us toward true worship—and Satan, who puts into the brain “Divellish Dreames” hoping to turn us toward evil.
In a very popular text which he revised throughout his life, Owen Felltham argues that the best use someone can make of their dreams is to gain greater self-understanding. The mind continues to work even in the depths of sleep, and dreams show us our inclinations.