For much of the 20th century, "good design" meant unornamented, largely rectilinear geometric forms, without the idiosyncrasies of sharp angles or compound curves. Modernist ideology generally held that function, material, and technique dictated the single best design for a particular purpose. Early 20th-century theorists like Le Corbusier, Zeisel wrote, "often referred to the sum of the forms and lines of their work as a form language rather than a style, because they felt they were creating eternal values." Zeisel admired many modernist designs, including what she calls "Le Corbusier's beautiful pavilion" at the Paris Exhibition of Decorative Arts. But she has always rejected the modernist design philosophy, with its claims to objective, eternal truths and its scorn for the audience's emotional response.

"The goal of the designer should be to give pleasure to the audience through his designs," she writes in On Design: The Magic Language of Things, published last year.

Her philosophy has become mainstream. From the iMac to Karim Rashid's blockbuster Garbino trash can, the touchstones of turn-of-the-century industrial design are full of personality and curves. Rounded, biomorphic "blobjects" may be less dominant than in the late 1990s, but designers have absorbed their chief lesson: "Form follows emotion," in the words of designer Hartmut Esslinger.