Yeats had a lifelong interest in mysticism, spiritualism, occultism and astrology. Themes explored include astrology and astronomy, ecology, science, occultism and mysticism, religion and philosophy. Bands often promote ethnic European paganism, occultism, or Satanism. As a mysticist, Pessoa was an enthusiast of esotericism, occultism, hermetism, numerology and alchemy. The earliest releases featured themes such as occultism, graphic violence, and Satanism. Blavatsky's Theosophical ideas were a form of "occultism". Radiesthesia has been described as a mixture of occultism and pseudoscience by critics. Some commentators have traced this position to the influence of postmodernism on contemporary occultism. These individuals typically were enthusiasts of occultism and the paranormal. It was probably the single greatest influence on twentieth century Western occultism. Pegg considered the album's theme to be a clash of "occultism and Christianity". Schopenhauer had a wide range of interests, from science and opera to occultism and literature. He had considerable influence on the development of early modern and modern occultism. "Chaos magic" as a branch of contemporary occultism is a product of the 1970s. The album explores gloomy lyrical subjects such as death, violence, and occultism.