Chapter 3 mostly deals with main principles of two-dimensional design and things connected to this subject, displaying a wide array of examples to go with it, so the reader can clearly see how they work in practice.
The chapter defines the pattern, one of the main principles of design, as a visual element that is systematically repeated over the extended area; patters are mostly based on a module or a basic visual unit. The chapter says patterns are often used to decorate walls, fabrics and books. Moreover, multiple parts of visual information can be unified in a composition using a certain pattern. In its turn, grid is a serious unifying power that is created with intersecting lines to increase continuity, encourage closure, strengthen proximity and also create containment. There are compositional grids, created with horizontal and vertical lines, and underlying grids.
Balance refers to distribution of weight within the composition and makes different compositional units work together. Weight is related to balance and refers to both inclination of shapes to float or sink and to relative importance of visual element within the design. Weight is influenced by size, type of the shape, value, orientation, location, and texture.
Scale and proportion create two types of size relationships, and both strongly affect overall compositional balance and emotional impact. Proportion is a relative size of visual elements within the image, while the scale is the size of a form compared to our human size.
Emphasis underlines particular part of a design and is created by a focal point. Both are used to attract attention and increase visual and conceptual impact. Emphasis can be achieved by isolating different visual elements, particular placement of the some of them within the image, and through contrast in scale, shape or color, when two or more forces are in opposition.