Over time you see the same behaviors and you group them together. You line them up in towers; then line up the towers into groups that represent different cognitive spaces. The diagram looks a lot like a city skyline. Once you have created the top half of the diagram, you focus on the lower half. Take the product features that you intend to create and align them beneath all the towers they support. In other words, you align the features that your business values beneath concepts that people mentioned. When you have finished, you will see areas of the mental model that are less supported than others, and you may have leftover functions that don’t support anything in the mental model.