Active Reading
Active reading is the idea that good reading is not passive reception but visible mental work. The reader asks questions, marks the book, tests claims, follows the structure, and tries to restate the author's position in his own words.
Adler and Van Doren frame this against the fantasy that reading is mainly absorption. A text, especially a hard one, does not pour understanding into the mind. It offers material that the reader has to work on. In that sense, reading resembles deliberate practice more than entertainment: effort is not a sign that something has gone wrong, but often the condition of growth.
The book organizes active reading around four questions: what is the book about as a whole, what is being said in detail and how, is it true, and what of it. Those questions turn reading into a sequence of obligations rather than a vague feeling of having "gone through" a text.
Active reading also includes external behavior. The reader underlines, annotates, writes questions, and keeps track of structure. This is why Adler defends marking books. A well-marked book is evidence that a conversation happened.
The concept belongs near critical thinking because it replaces passive agreement with disciplined judgment. It also belongs near learning is memory, because active engagement produces better encoding than untouched exposure does.