on drawing

I rediscovered drawing, after a break of several years, in the most delightful fashion whilst playing with my youngest nephew, who was then only three or four years old. ( He is now almost fifteen).
We devised a game, which came to be known as "chalk lines", and was played on the long paths of my parents back garden. The chalk lines were drawings of railway lines, made in children's chalks, upon which we ran his small die-cast metal toy locomotives and carriages. The lines would stretch from one end of the garden just outside the house to the bottom of the garden and were beautiful, spidery drawings. I made a number of polaroid images during those times, some in black and white, showing the delicacy of the white lines against the aged concrete path, and some of Patrick himself. Two of the latter I have especial affection for; they show Patrick, crouched double on the path in the manner of the very young, busily engaged in covering paving stones with a mass of white chalk, his interpretation of a blizzard, or 'whiteout', through which hazzard we were to manoevre his engines and carriages.
The practice of drawing thus with Patrick was stimulating, and invigorating, but I was not able to further the experience or develop a practice of drawing for myself.
Why was it not possible for my drawing practice to have grown from the chalk lines on the garden path? Those drawings are severed from my present experience as though they had been made by another person.
The closest I have to those childish lines, are the drawings of rainbows, made many years hence, and expressive of a very different experience.