A Treatise Concerning the Principles of Human Knowledge

Although Berkeley titles this section “Part 1,” there is in fact no Part 1I; Berkeley had originally planned to publish a second part but later changed his mind.

Part 1 opens with the assertion that what we call the objects of human knowledge are in fact ideas imprinted on the senses. By using our senses to engage with objects we form ideas about their nature. This is how we perceive, imagine, and remember the world around us. However, we can make a distinction between the mental process of perceiving and the being that perceives. Section 2 describes the being that does the thinking, imagining, remembering, etc., as “mind, spirit, soul, or myself” (24).

In Section 3, Berkeley states his first major principle: “the existence of an idea consists in being perceived” (24). Expressed in Latin terms, this principle is “esse is percipi” (to be is to be perceived). Properly speaking, we do not perceive objects but our own “ideas or sensations” (25) about the objects. Sections 4 and 5 discuss the common mistake of believing in abstract ideas. Idea cannot exist unperceived, just as senses cannot exists outside of a mind’s sensory perception. Section 6 states that some concepts are so obvious that they can be difficult to articulate. The proof of Berkeley’s ideas is in the reader’s own attempt to separate their thoughts from the things they are perceiving.

Berkeley finds it “plainly repugnant” that sensible objects should exist unperceived because this negates the importance of God’s role in creating the universe. Light, color, heat and cold, size and extension, motion, etc., are “sensations, notions, ideas, or impressions on the sense” (25); they do not have an existence independent from us, or by extension, from God. Berkeley specifies that all things are perceived by the mind of God, meaning that they do not simply cease to exist when a human being is not perceiving them, which is one of the objections he confronts later in the Treatise.