Following Bridget Riley on drawing-as-thinking, I have been reading Jim Savage’s fascinating collection of writings by John Berger on the topic of drawing.  Although Berger does not say so, he is talking primarily about representational drawing – the drawing of things in the world (whether seen or remembered) or things in some imagined world – not abstract drawing.  Some excerpts:

• “For the artist drawing is discovery.  And that is not just a slick phrase, it is quite literally true.  It is the actual act of drawing that forces the artist to look at the object in front of him, to dissect it in his mind’s eye and put it together again; or, if he is drawing from memory, that forces him to dredge his own mind, to discover the content of his own store of past observations.” (page 3)
• “It is a platitude in the teaching of drawing that the heart of the matter lies in the specific process of looking.  A line, an area of tone, is not really important because it records what you have seen, but because of what it will lead you on to see.  Following up its logic in order to check its accuracy, you find confirmation or denial in the object itself or in your memory of it.  Each confirmation or denial brings you closer to the object, until finally you are, as it were, inside it:  the contours you have drawn no longer marking the edge of what you have seen, but the edge of what you have become.  Perhaps that sounds needlessly metaphysical.  Another way of putting it would be to say that each mark you make on the paper is a stepping-stone from which you proceed to the next, until you have crossed your subject as though it were a river, have put it behind you.” (page 3)
• “A drawing is an autobiographical record of one’s discovery of an event – seen, remembered or imagined.” (page 3)
• “A drawing of a tree shows, not a tree, but a tree-being-looked-at.  . . .  Within the instant of the sight of a tree is established a life-experience.” (page 71)
• “All genuine art approaches something which is eloquent but which we cannot altogether understand.  Eloquent because it touches something fundamental.  How do we know?  We do not know.  We simply recognize.”   (page 80)
• “Art cannot be used to explain the mysterious.  What art does is to make it easier to notice. Art uncovers the mysterious. And when noticed and uncovered, it becomes more mysterious.”  (page 80)
• “The pen with which I’m writing is the one with which I draw.  And there are times, like tonight, when it won’t flow and when it demands a bath or a hand moving differently.  All drawings are a collaboration, like most circus-acts.” (page 110)
• “where are we, during the act of drawing, in spirit?  Where are you at such moments – moments which add up to so many, one might think of them as another life-time?    Each pictorial tradition offers a different answer to this query.  For instance, the European tradition, since the Renaissance, places the model over there, the draughtsman here, and the paper somewhere in between, within arms reach of the draughtsman, who observes the model and notes down what he has observed on the paper in front of him.   The Chinese tradition arranges things differently.  Calligraphy, the trace of things, is behind the model and the draughtsman has to search for it, looking through the model.   On his paper he then repeats the gestures he has seen calligraphically.  For the Paleolithic shaman, drawing inside a cave, it was different again.  The model and the drawing surface were in the same place, calling to the draughtsman to come and meet them, and then trace, with his hand on the rock, their presence.” (page 123)

Reference:
John Berger [2005]:  Berger on Drawing.  Edited by Jim Savage.  Aghabullogue, Co. Cork, Eire:  Occasional Press.  Second Edition, 2007.
I have written more on the relationships between hand and mind and eye and object here.