Everyone by now has seen the whimsical cone-shaped kettle with the little plastic birdie affixed to its spout, designed by the architect Michael Graves. Since its introduction in 1985 by Alessi, the northern-Italian home-furnishings manufacturer, approximately 1.5 million units of what is, as kettles go, an expensive item have been sold.

A version of this article appeared in the December 2006 issue of Harvard Business Review.