The various readings which I now conducted with skill and discretion was digested according to the precept and model of Mr. Locke into a large Commonplace book, a practice however which I do not strenuously recommend. The action of the pen will doubtless imprint an idea on the mind as well on the paper; but I question whether the benefits of this laborious method are adequate to the waste of time, and must agree with Dr. Johnson, 'that twice read is commonly better remembered as what is transcribed.'Locke's commonplace books are discussed in these entries. One of the reasons why Gibbon felt mere excerpts are a "waste of time" is that he later opted for a method of abstracts or "extracts made with reflection":
When we have read with attention, there is nothing more useful to the memory than extracts. I speak not of those collections, or adversaria, which may be serviceable in their own way, but of extracts made with reflection, such as those of Photius, and of several of our modern journalists. I purpose in this manner to give an account to myself of my reading. My method will vary with the subject. In works of reasoning, I will trace their general plan, explain the principles established, and examine the consequences deduced from them. them. A philosopher is unworthy of the name, whose work is not most advantageously viewed as a whole. After carefully meditating my subject, the only liberty I shall take, is that of exhibiting it under an arrangement different perhaps from that of my author. Works of fancy contain beauties, both of plan and of execution: I shall be attentive to both. History, if little known, deserves an abridgment. I shall extract such particulars as are new. Throughout, I shall give my opinion with becoming modesty, but with the courage of a man unwilling to betray the rights of reason. In this compilement, I shall collect my scattered thoughts, with the reflections of every sort that occur in my search for truth. For I shall continue to search for the truth, though hitherto I have found nothing but probability.The language may be a bit quaint or outdated, the principles are still sound, or so I would argue. They more or less describe my method of summarizing (as inspired by Luhmann).
1. Memoirs of the Life and Writing of Edward Gibbon. Edited, with Introduction and Notes by Oliver Farrar Emerson (Boston: Ginn and Company, 1898), p. 81.
2. The Miscelleneous Works of Edward Gibbon, Esqu., Memoirs of His Life and Writings, Composed by Himself. Illustrated from His Letters, with occasional Notes and Narrative by John, Lord Sheffield (London, 1837), p. 398. It's available on the Internet: here.