Keep a question list

Unanswered questions are more useful when separated from ordinary highlights.

The observation

Reading becomes more durable when it begins with a question. Mark only the passages that alter the question, supply evidence, or deserve comparison with another source.

Keep a question list is less a rule than a useful test: does the arrangement make the next encounter clearer?

In practice

At the end, write a short account in your own words. Record the source and page, but also record why the passage mattered at that moment. That second line often becomes the useful one.

A closing note

Notes should return you to the argument, not replace it. Leave enough space for disagreement and later revision.