Locke distinguishes between ideas of primary qualities and ideas of secondary qualities (pages 178-181): secondary qualities (smell, taste, color, sound, texture) are associated with different sense organs and are produced in us but have no objective reality in external things; primary qualities (size, shape, weight, density) are objective properties of material bodies that produce sensations through causal influence.

The Enlightenment is characterized not only by the light of reason in thinking but also by the rule of reason in living — that is, the idea that when we are ruled by reason we are freed from other causal conditions and compulsions, whereas acting out of emotional impulse means we are driven and not free.

The terminal enlightenment refers to the light of Reason, understood in context as the light of scientific knowledge gained by objective scientific methods (whether inductive or deductive) and the kind of objectivity and conclusiveness that science claimed.

The Enlightenment was skeptical of tradition and authority, and frequently gave no place to revelation; where Christians participated in the Enlightenment and discussed revelation, it was treated as an add-on supplementary to reason rather than as an underlying perspective that helps us understand the rest.

The Enlightenment was opposed to dogmatic systems; the big system builders like Descartes and Spinoza belong to the early 17th century rather than 18th century Enlightenment because those system builders claimed a kind of systematic knowledge which could not be established by scientific means alone.

David Hume is a radical philosophical skeptic who is skeptical about the possibility of achieving objective knowledge with certainty in the Enlightenment sense, and develops in its place an account of how belief arises and seems to be justified as distinct from that dogmatic kind of knowledge.

Voltaire and the French philosophers (philosophes) were part of a group of philosophical skeptics about the possibility of knowledge, representing the Enlightenment's self-critical turn.

John Locke, with emphasis on rights to life, liberty, and property, and other theories of rights developed in the Enlightenment, form the foundation of French and American political heritage; the rule of laws governed by Constitution represents the rule of Reason.

Romanticism reacted against Enlightenment Rationalism by reverting to the freedom of emotion and the creative genius, idealizing freedom as emotional self-expression rather than detached rational deliberation.

There is a trajectory from Renaissance emphasis on political liberties through Enlightenment individual rights to Romantic creative self-expression to existentialist absolute idealization of freedom, representing an increasing absolutization and idealization of the notion of individual freedom.

John Locke is characterized by both Enlightenment spirit and Puritan heritage; his father was a signatory of the Westminster Confession of Faith, the classic Presbyterian document of the counter-reformation 17th century, and this theological background influences his philosophical work.

Locke applies the Newtonian atomistic model of particles of matter combined and moved according to fixed laws to three domains: his theory of ideas (simple ideas combined according to fixed laws of association), his psychology, and his social philosophy (social atoms/individuals joining together according to laws of a social contract).

Locke explicitly states at the opening of the Essay Concerning Human Understanding that understanding sets man above other sentient beings and gives him all the advantage and dominion he has over them, combining Enlightenment rationality with Puritan-Reformed emphasis on human dominion over creation.

Locke makes a distinction between opinion and knowledge as a reshaping of the Platonic distinction, where knowledge must be objective, certain, and scientifically and logically guaranteed, while opinion is different; and recommends we ought to regulate our assent and moderate our persuasions through understanding these bounds.

Locke defines 'idea' as whatever is the object of understanding when a man thinks; this reflects a Cartesian starting point where the mind is directly aware of its own ideas, and all we directly know are our ideas, requiring proof or demonstration to infer anything about external things like bodies, other minds, or God.

Locke's argument against innate ideas follows a logical structure: if ideas are innate, they would be universally known; but there are no universal ideas about God and morality (evidenced by children, idiots, and cultural diversity); therefore, ideas are not innate.

On page 168, Locke accounts for the universal idea of God by arguing that the visible marks of extraordinary wisdom and power appear plainly in creation, such that any rational creature reflecting seriously on them cannot miss discovering a deity — a position that paraphrases Romans 1 and reflects Puritan/Calvinist theology about natural knowledge of God.

According to Locke, the consciousness or human mind is a blank tablet (tabula rasa) — like a blank piece of paper on which experience leaves marks — providing the foundational metaphor for how ideas originate through sensation.

Ideas come from both internal and external senses; the external senses are the five familiar sensory modalities, while the internal sense involves reflection on our own mental states, including reflection on blueness as an afterimage and reflection on mental acts like thinking, wishing, and believing.

Simple ideas have the characteristic of being clear and distinct (echoing Descartes), but for Locke they are not innate or intuitive — they are given to us through sensation and are passively received rather than actively intuited.