ancient manuscript he located. Journals which publish regularly on the topic of Alchemy include 'Ambix', published by the Society for the History of Alchemy and Chemistry, and 'Isis', published by The History of Science Society. Core concepts Western alchemical theory corresponds to the worldview of late antiquity in which it was born. Concepts were imported from Neoplatonism and earlier Greek cosmology. As such, the classical elements appear in alchemical writings, as do the seven classical planets and the corresponding seven metals of antiquity. Similarly, the gods of the Roman pantheon who are associated with these luminaries are discussed in alchemical literature. The concepts of prima materia and anima mundi are central to the theory of the philosopher's stone. Magnum opus The Great Work of Alchemy is often described as a series of four stages represented by colors. nigredo, a blackening or melanosis albedo, a whitening or leucosis citrinitas, a yellowing or xanthosis rubedo, a reddening, purpling, or iosis Modernity Due to the complexity and obscurity of alchemical literature, and the 18th-century disappearance of remaining alchemical practitioners into the area of chemistry, the general understanding of alchemy has been strongly influenced by several distinct and radically different interpretations. Those focusing on the exoteric, such as historians of science Lawrence M. Principe and William R. Newman, have interpreted the 'decknamen' (or code words) of alchemy as physical substances. These scholars have reconstructed physicochemical experiments that they say are described in medieval and early modern texts. At the opposite end of the spectrum, focusing on the esoteric, scholars, such as Florin George Călian and Anna Marie Roos, who question the reading of Principe and Newman, interpret these same decknamen as spiritual, religious, or psychological concepts. New interpretations of alchemy are still perpetuated, sometimes merging in concepts from New Age or radical environmentalism movements. Groups like the Rosicrucians and Freemasons have a continued interest in alchemy and its symbolism. Since the Victorian revival of alchemy, "occultists reinterpreted alchemy as a spiritual practice, involving the self-transformation of the practitioner and only incidentally or not at all the transformation of laboratory substances", which has contributed to a merger of magic and alchemy in popular thought. Esoteric interpretations of historical texts In the eyes of a variety of modern esoteric and Neo-Hermeticist practitioners, alchemy is fundamentally spiritual. In this interpretation, transmutation of lead into gold is presented as an analogy for personal transmutation, purification, and perfection. According