Why a fast-spinning pierced body does not hide what is behind it
On 'real' motions and vision, with the example of women's yarn-winders
This text page opens Leonardo's treatment of 'real' motions, leaving 'spiritual' ones to others. He observes that a body moving with swift impetus, if near the eye and not much larger than it, never blocks the eye's view of what lies behind it. His example is the spinning yarn-winders women use to gather thread, called arcolai by the Florentines and bicocche by the Lombards: being pierced through and turning so fast, they hide nothing behind them.
On this page
A swiftly moving body near the eye does not conceal what lies behind it
A real motion made with swift impetus will never keep the eye from seeing the thing behind the moving body, provided that body is near the eye and not much larger than the eye itself. The observation ties the visibility of a background to the speed and nearness of the moving object.
The women's yarn-winders: arcolai and bicocche
Leonardo cites the winding instruments women use to gather their threads, called arcolai by the Florentines and bicocche by the Lombards. Because they are pierced through and turn so fast in their circular motion, they do not block the eye's view of anything behind them.