Reading furnishes the mind only with materials of knowledge; it is thinking that makes what we read ours.

The remark is commonly attributed to John Locke in connection with his educational writings, where he stresses that learning is not mere accumulation of information but the active formation of judgment. In the late seventeenth century, Locke was reacting against scholastic habits of rote study and bookish “authority,” urging instead that students be trained to reason, reflect, and test ideas for themselves. The sentiment fits Locke’s broader empiricist outlook: experience (including reading) supplies the raw materials, but the mind must work on them—comparing, abstracting, and drawing conclusions—if knowledge is to become genuinely one’s own rather than borrowed from others.

The sentence distinguishes passive intake from active ownership of ideas. Reading can stock the mind with facts, arguments, and examples, but without reflection those remain external—something merely encountered rather than understood. “Thinking” here implies testing what one reads against experience, drawing inferences, relating it to other knowledge, and forming independent judgments. The claim also carries an ethical and pedagogical edge: true learning requires intellectual labor by the learner, not just authority borrowed from books. In Lockean terms, knowledge becomes “ours” when we can use it—explain it, evaluate it, and apply it—rather than simply repeat it.