Reid himself is always more sparing with them than his disciples. He distinguishes two classes: first principles of necessary truth, and first principles of contingent truth or truth of fact. As first principles of necessary truth he cites, besides the axioms of logic and mathematics, grammatical, aesthetic, moral, and metaphysical principles (among the last belong the principles: "That the qualities which we perceive by our senses must have a subject, which we call body, and that the thoughts we are conscious of must have a subject, which we call mind"; "that whatever begins to exist, must have a cause which produced it"). He lays down twelve principles as the basis of our knowledge of matters of fact, in which his reference to the doubt of Berkeley and Hume is evident. The most important of these are: "The existence of everything of which I am conscious"; "that the thoughts of which I am conscious, are the thoughts of a being which I call myself, my mind, my person"; "our own personal identity and continued existence, as far back as we remember anything distinctly"; "that those things do really exist which we distinctly perceive by our senses, and are what we perceive them to be"; "that we have some degree of power over our actions, and the determinations of our will"; "that there is life and intelligence in our fellow-men"; "that there is a certain regard due... to human authority in matters of opinion"; "that, in the phenomena of nature, what is to be, will probably be like what has been in similar circumstances." [Footnote 1: In the sense of "chief founder"; cf. McCosh's _Scottish Philosophy_, 1875, pp. 36, 68 _seq_., which is the standard authority on the school as a whole.--TR.] The widespread and lasting favor experienced by this theory, with its invitation to forget all earnest work in the problems of philosophy by taking refuge in common sense, shows that a general relaxation had succeeded the energetic endeavors which Hume had demanded of himself and of his readers. With this declaration of the infallibility of common consciousness, the theory of knowledge, which had been so successfully begun, was incontinently thrust aside, although, indeed, empirical psychology gained by the industrious investigation of the inner life by means of self-observation. James Beattie continued the attack on Hume in his _Essay on the Nature and Immutability of Truth in Opposition to Sophistry and Skepticism_, 1770, on the principle that wisdom must never contradict nature, and that whatever our nature compels us to believe, hence whatever all agree in, is true. In his briefer dissertations Beattie discussed Memory and Imagination, Fable and Romance, the Effects of