The Origin and Classification of Ideas
This chapter (1) expounds Locke’s empiricist principle that all of our ideas are derived from experience, and (2) offers a clarification of the structure of Book II of the Essay. Regarding (1), it explains his twofold use of the term “idea” to mean both any sensory or introspectible state and any concept, his distinctions between ideas of sensation and ideas of reflection and between simple and complex ideas, and his classification of simple ideas. It identifies some noteworthy points about the idea of solidity. Regarding (2), it provides a clarification of the organization of Book II, in light of the facts that Locke (a) digresses into the theory of primary qualities and secondary qualities in Book II Chapter viii before continuing his aetiology of ideas, and (b) discusses several complex ideas of reflection, in Book II Chapters x and xi, before officially turning to complex ideas in Chapter xii.