How to Summarize Accurately

When you summarize, you report only that portion of a source most relevant to your argument, usually only its main points. Because a summary leaves out details, it is shorter than the original—often much shorter. If only one section of a source is relevant to your argument, readers will not expect you to summarize the whole, but they will expect you to present enough context for them to understand how the part you summarize fits into the source's argument.

Here is an example of a summary, taken from an article written by Steffen Ducheyne. Ducheyne's article concerns how Galileo used arguments about what causes things to move. Here, Ducheyne summarizes one of Galileo's early books, De Motu (On Motion):

Let me first of all take stock of the present discussion. De Motu, written between 1589 and 1592, is one of Galileo's early scientific works on what we today would roughly call “mechanics.” That in De Motu Galileo wished to establish a causal explanation of motion (and acceleration) is accepted by all scholars. According to Galileo, falling bodies are moved by an internal cause; projectiles by an external one. Galileo indeed claimed that he wished to determine the hidden causes of observable effects . . . . In dealing with the cause of acceleration, Galileo clarified that he wanted to discover the true, essential and not the accidental cause of acceleration. Acceleration is an accidental feature of motion, caused by the gradual overtaking of the intrinsic weight of a body during fall, after being lifted (and the weight being diminished) by an impressed force. Scholars begin to disagree, however, on the presence and importance of causal explanations in the period after this early work.


Source: Steffen Ducheyne, “Galileo's Interventionist Notion of 'Cause,'” Journal of the History of Ideas, vol. 67, no. 3 (2006): 443-64.

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For the purposes of his argument, Ducheyne does not need to rehearse all the details of Galileo's long, technical book. But Ducheyne does want his readers to understand the main issue in De Motu: that Galileo's goal was to uncover the “hidden causes” of motion, not the “accidental feature[s]” that are easily observed. So he leaves out most of Galileo's reasons and all of his evidence, reporting only the part of De Motu that matters most to Ducheyne's own argument.

NOTE: When you summarize, you must use your own words. Also, you must always cite the source of every summary, both in your text and in your bibliography or works cited. If you fail to do so, even by accident, you open yourself to the charge of plagiarism.<

How to Construct a Summary<

  • Decide what part of the source is most relevant to your argument.
  • Pick out the most important sentences in that part of the source. In most cases, you'll focus on the main points.
  • Paraphrase those sentences. If they include any important or memorable phrases, quote those in your paraphrases. List the paraphrased sentences in the order they occur in the original.
  • Add any other information that readers might need to understand how your paraphrased sentences connect to one another.
  • Revise the list so that it reads not like a list but like a paragraph.

How to Mix Quotation with Summary<

A long summary can make readers feel that you and they are too distant from an important source. So when you write a summary as long as half a page, look for memorable phrases that you can quote within your summary.

Colomb and Williams emphasize that drafting is “an act of discovery” that can fuel a writer's creative thinking. They acknowledge that some writers have to draft carefully and stick closely to their outlines, but they advise writers to draft as freely and as openly as they can. They encourage even slow and careful drafters to be open to new ideas and surprises and not to be limited by what they do before drafting. They still stress the value of steady work that follows a plan: for example, writing a little bit every day rather than all at once “in a fit of desperate inspiration.” But they show writers how to make the best of a plan while hoping that you will “discover what your storyboard has missed.”


Source: Kate L. Turabian. A Manual for Writers of Research Papers, Theses, and Dissertations, Seventh Edition : Chicago Style for Students and Researchers. Revised by Wayne C. Booth, Gregory G. Colomb, Joseph M. Williams, and University of Chicago Press Editorial Staff. (University of Chicago Press, 2007), 83-7.

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When you add a few quotations to your summary, you seem a more lively writer. You give readers an idea of your source without quoting so much that your paper seems a cut-and-paste job. If you have pages that are mostly summary and paraphrase, add a few notable quotations that will liven up your writing.