This is a text about how we see: the environment around us (its surfaces, their layout, and their colours and textures; where we are in the environment; whether... » 

This is a text about how we see: the environment around us (its surfaces, their layout, and their colours and textures; where we are in the environment; whether or not we are moving, and if we are, where we are going; what things are good for; and how to do things, such as threading a needle. «