The act of drawing is as embedded in the human DNA as nest-building is to birds. The impetus is multi-facetted-intuitive, instinctive, rational, deliberate and serendiptous, even accidental.  Applied to design, the duality of medium  (in my case, pen &  paper) is very near to, if not at the epicenter of conception and ideation.
As Paul Klee so notably observed-the point moves to create a line, the line moves to create a plane, the plane moves to create a volume. As a designer, one can never say with absolute certainty they have arrived...