A part of the process of Syntopical Reading with the goal of understanding a text in light of other sources. One should always strive to read the source material first, then read extrinsic sources in chronological order. Examples of extrinsic sources include:
- Relevant personal experience
- Other books, essays, and articles
- Commentaries and abstracts on the source material
- Reference books
How to read a book by Mortimer Jerome Adler, Charles Van Doren