The readings increasingly came to involve occult or esoteric themes. Emanationism is a common teaching found in occult and esoteric writings. Instead he invested most of his time in the study of metaphysical and esoteric treatises. In the eyes of a variety of esoteric and Hermetic practitioners, alchemy is fundamentally spiritual. Sufism embodies a number of cultures, philosophies, central teachings and bodies of esoteric knowledge. Pythagoreanism was the system of esoteric and metaphysical beliefs held by Pythagoras and his followers. This requires a thorough study of esoteric doctrines and/or religions. A is often connected with ancient wisdom or sometimes with esoteric knowledge. Absolute Bodhicitta is a more esoteric Tantric Teaching. Mystery religions require a period of indoctrination before granting access to esoteric knowledge. Isis continues to appear in modern esoteric and pagan belief systems. The Yellow Emperor was credited with an enormous number of cultural legacies and esoteric teachings. De Acosta, a theosophist, was interested in esoteric spirituality. Boyd had always expressed an interest in esoteric religions. The goddess is viewed as the heart of the most esoteric Saiva traditions.