The external form of its last chapters in particular proves them to be in the nature of notes, intended to clear the author's own mind, rather than final conclusions ready for the reader's enlightenment. This fact is amply authenticated by the man best in the position to know: Friedrich Engels, who edited the second volume. In his introduction to the second volume he reports in detail on the conditions of the preliminary studies and the manuscripts Marx had left, which were to form the basis of this volume: 'The mere enumeration of the manuscripts left by Marx as a basis for Volume II proves the unparalleled conscientiousness and strict self-criticism which he practised in his endeavour to fully elaborate his great economic discoveries before he published them. This self-criticism rarely permitted him to adapt his presentation of the subject, in content as well as in form, to his ever widening horizon, which he enlarged by incessant study. 'The material ... consists of the following parts: First, a manuscript entitled "A contribution to the Critique of Political Economy", containing 1,472 quarto pages in 23 divisions, written in the time from August, 1861, to June, 1863. It is a continuation of the work of the same title, the first volume of which appeared in Berlin, in 1859.... This manuscript, valuable though it is, could not be used in the present edition of Volume II. 'The manuscript next following in the order of time is that of Volume III.... 'The period after the publication of Volume I, which is next in order, is represented by a collection of four manuscripts for Volume II, marked I-IV by Marx himself. Manuscript I (150 pages) presumably written in 1865 or 1867, is the first independent, but more or less fragmentary, elaboration of the questions now contained in Volume II. This manuscript is likewise unsuited for this edition. Manuscript III is partly a compilation of quotations and references to the manuscripts containing Marx's extracts and comments, most of them relating to the first section of Volume II, partly an elaboration of special points, particularly a critique of Adam Smith's statements as to fixed and circulating capital and the source of profits; furthermore, a discussion of the relations of the rate of surplus-value to the rate of profit, which belongs in Volume III. The references furnished little that was new, while the elaborations for Volumes II and III were rendered valueless through subsequent revisions and had to be ruled out for the greater part. Manuscript IV is an elaboration, ready for printing, of the first section and the first chapters of the second section of Volume II, and has been used in its proper place. Although it was found that this manuscript had been written earlier than Manuscript II, yet it was far more finished in form and could be used with advantage for the corresponding part of this volume. I had to add only a few supplementary parts of Manuscript II.