When arguing for materialism in his "Examination" Priestley strongly suggested that there was no mind-body duality. Such opinions shocked and angered many of his readers and reviewers who believed that for the soul to exist, there had to be a mind-body duality. In order to clarify his position he wrote "Disquisitions relating to Matter and Spirit" (1777), which claimed that both "matter" and "force" are active, and therefore that objects in the world and the mind must be made of the same substance. Priestley also argued that discussing the soul was impossible because it is made of a divine substance and humanity cannot gain access to the divine. He therefore denied the materialism of the soul while simultaneously claiming its existence. Although he buttressed his arguments with familiar scholarship and ancient authorities, including scripture, he was labeled an atheist. At least a dozen hostile refutations of the work were published by 1782.