Growth in understanding rests partly on experience, partly on education, and partly on self-reflection. Donald Schon in The Reflective Practitioner identifies a distinguishing trait of the high performers as their ability to reflect on practice [that is looking carefully at what they do and how to improve] at the same time as they reflect in practice [that is to consider what could be done better or differently while they are doing the task]. The continuous refinement of performance by these reflections is well documented in his book.