Back in Blakeney (~2002), John, trying to figure out why someone who did so much work was making so little progress, said to me: What's holding you back is your inability to visualise.

Visualisation is not seeing in the mind something that isn't there but using the imagination to see something you have been told is there but that you cannot sense yet. You could have been told by the teacher or, more commonly, if you are working, by your own intuition.