Using contrast in structure, we create a juxtaposition of differences in typefaces. The most common way to do this is to contrast typefaces of different moods and aesthetics, for example, a straightforward and neutral sans serif typeface with elegant and traditional serifs or bold and authoritative slab serifs. In his book Design with Type, Carl Dair compares the contrast of structure to an orator who changes not only the volume of his voice but its very quality to suit his words.