In The New, New Thing, Michael Lewis refers to the term "business model" as a term of art, essentially describing a business's plan for how to make money. Yet your business model (and your inherent assumptions about your company) shape how nimble you are—and how good you are at making money. In other words, what you think about your business shapes your business in the future. So if your assumptions are wrong, you have space to make your business stronger. Once you improve your assumptions, you can change the way you do business for the better. The key is understanding and interrogating your mistakes.