Several biographies have been published of Carr's life with unsubstantiated speculations. His teachings extend beyond metaphysical speculations and philosophy. Modern era historians still differ on their speculations and opinions about it. There are several conspiracy speculations related to his death. Much of Scheele's later theoretical speculations were based upon Stahl. Sources had to be solid, not speculations and rationalizations. Sources had to be hard, not speculations and rationalizations. The tantra practices are secretive, subject to speculations and criticism. Speculations regarding its name however, exist. Many of the speculations regarding technical specifications proved accurate. Chakras became a part of mainstream esoteric speculations in the 1980s and 1990s. A number of popular etymological speculations were offered by early modern Rabbinic authorities. Public speculations and debate however continued. But the bulk of these texts dealt with astronomical speculations and magical lore. An interesting point in his speculations is the insistence that nothingness is something positive.