A skilled surgeon operates on many levels at once. She understands how to use each of the instruments and for what purpose. She has mastered certain basic techniques such as making an incision and suturing a wound. But she also needs to be able to see the big picture: What is the purpose of the operation? How do the individual skills and techniques need to fit together and in what order? She needs to know how to apply the right tool at the right time in order to accomplish the purpose of the operation.