"What is the difference between merely knowing (or remembering, or memorizing) and understanding? ...A thing or idea seems meaningful only when we have several different ways to represent it–different perspectives and different associations. ...Then we can turn it around in our minds, so to speak: however it seems at the moment, we can see it another way and we never come to a full stop. In other words, we can 'think' about it. If there were only one way to represent this thing or idea, we would not call this representation thinking."