from whence a grid?

I recently saw a wonderful exhibit on the works of M.C.Escher at the Art Museum.

The museum displayed many of his sketches, and I was intrigued at the meticulously penciled grids he had drawn on some of them to guide his lines. This is no surprise to me as an amateur artist. I am well aware that the drawing of a grid is often an extremely useful first step of a sketch, depending on the artist intends to draw. The grid establishes a structure for the shapes to come. I have been in some classes and seen the videos on perspective drawing demonstrating how to guide the straight lines from the vanishing point to create well-angled roofs of buildings. I had seen the 'before' and 'after' pictures of art - before and after perspective drawing (implication: before and after the introduction of rationality into art). I listened when they pointed at the 'before' and 'after' pictures to demonstrate that one of them looked more 'real.'

But, as I was contemplating the place of grid and straight-line drawing in the training of an artist, and as biked through the valley of the Springwater Corridor where for a brief span of time the only man-made object was the curving trail beneath me, and as I walked with my empty breakfast bowl back between the contoured trees at the edge of the park, I started to wonder more seriously ...

Nature is not made of straight lines.
Whatever first gave someone the idea of grids and lines?
And when did we begin imposing grids and lines as an internal or background structure for things?
And why am I only thinking of this now?