Like the British philosopher Bernard Williams, Nagel believes that the rise of modern science has permanently changed how people think of the world and our place in it. A modern scientific understanding is one way of thinking about the world and our place in it that is more objective than the common sense view it replaces. It is more objective because it is less dependent on our peculiarities as the kinds of thinkers that people are. Our modern scientific understanding involves the mathematicized understanding of the world represented by modern physics. Understanding this bleached out view of the world draws on our capacities as purely rational thinkers and fails to account for the specific nature of our perceptual sensibility. Nagel repeatedly returns to the distinction between "primary" and "secondary" qualities, that is, between primary qualities of objects like mass and shape, that are mathematically and structurally describable independent of our sensory apparatuses, and secondary qualities like taste and color, which depend on our sensory apparatuses.