[28] We have everywhere called to mind, maintained, and confirmed by the errors of those who have dared to break it, this rule of true psychological analysis, that, before passing to the question of the origin of an idea, a notion, a belief, any principle whatever, the actual characters of this idea, this notion, this belief, this principle, must have been a long time studied and well established, with the firm resolution of not altering them under any pretext whatever in wishing to explain them. We believe that we have, as Leibnitz says, settled this point. See 1st Series, vol. i., Programme of the Course of 1817, and the Opening Discourse; vol. iii., lecture 1, _Locke_; lecture 2, _Condillac_; lecture 3, almost entire, and lecture 8, p. 260; 2d Series, vol. iii., _Examen du Systeme de Locke_, lecture 16, p. 77-87; 3d Series, vol. iv., _Examination of the Lectures of M. Loremquiere_, p. 268. [29] This theory of spontaneity and of reflection, which in our view is the key to so many difficulties, continually recurs in our works. One may see, vol. i. of the 1st Series, in a programme of the Course of 1817, and in a fragment entitled _De la Spontaneite et de la Reflexion_; vol. iv. of the same Series, Examination of Reid's Philosophy, _passim_; vol. v., Examination of Kant's System, lecture 8; 2d Series, vol. i., _passim_; vol. iii., Lectures on Judgment; 3d Series, _Fragments Philosophiques_, vol. iv., preface of the first edition, p. 37, etc.; it will be found in different lectures of this volume, among others, in the third, On the value of Universal and Necessary Principles; in the fifth, On Mysticism; and in the eleventh, Primary Data of Common Sense. [30] On immediate abstraction and comparative abstraction, see 1st Series, vol. i., Programme of the Course of 1817, and everywhere in our other Courses. [31] On M. de Biran, on his merits and defects, see our _Introduction_ at the head of his Works. [32] See lecture 1. [33] See vol. i. of the 1st Series, course of 1816, and 2d Series, vol. iii., lecture 18, p. 140-146. [34] We have developed this analysis, and elucidated these results in the 17th lecture of vol. ii. of the 2d Series.