 An Essay Concerning the Use of Reason, Collins’ first book, was published anonymously in 1707 a little before his Letter to Mr. Dodwell. The main thrust of the book is to reject religious mysteries. Collins starts his approach to the issues of religion and reason along the same lines that Locke does. He defines reason as “that faculty of the Mind, whereby it perceives the truth, Falsehood, Probability or Improbability of Propositions” (1707 [1984: 3]). Propositions consist of words “which stand for Ideas concerning which some agreement is affirm’d or deny’d” (1707 [1984: 3–4]). Thus he accepts Locke’s definition of knowledge. He also distinguishes in the way Locke does intuitive, demonstrative and probable truths, and treats claims about revelation as probable propositions that largely derive from testimony. Perhaps one diversion from Locke is that Collins distinguishes between two different kinds of probability. The stronger kind resembles demonstration but the connection between ideas is merely probable. The weaker kind of probability is a testimony. Collins’ position is that a person is not expected to believe anything that is not comprehensible by the human intellect. So, if terms take on meanings that cannot be understood, humans cannot be expected to believe them.