There is no such thing as a line in real life, but the eyes and brain accept the long thin roll of carbon as though it were a common thing.
A common thing to see each each of us wrapped inside a soft black thread as we walk from our cars or sit on the back porch telling stories.
We look at a drawing and recognize faces, names; the shape of hats, elbows, and tired eyes and say, "that's him alright", or "you call that art?" For me, drawing is like fishing on a square white lake pulling out the endless shapes that live just beneath the surface.