The idea that here’s a piece of paper and on it a line and the line is drawn in a way to reflect as closely as possible what I see in a real object from a very specific viewpoint.

The idea that wherever I take this drawing someone can see my once view of a selected object and get ideas about my once view, feel it, sense that there might have been a reason for me to draw that line and perhaps somehow even feel or intuit or know that reason from the facts apparent in the drawing.

The idea that this very indirect path is important.