What makes a teacher great?

The ability to see the one and the many. This was the immediate thought which came to mind and I’m running with it. 

To be able to ascertain  how individual pupils are shaped and how they best learn is important. —A principle that is not limited to the school classroom or formal education. As is knowing and understanding how the class as a whole is shaped and functions 

I recognize that this is something which in some classrooms—due to class size, resources etc.—may be difficult or even nigh on impossible.

However, if the situation in which one is teaching provides a suitable canvas, holding the tension between the one and the many, I hope, is still possible.