The traditional view of understanding the working mechanism of visual perception can be traced back to Descartes, a French philosopher in the 16th century  Descartes believes that the brain will first construct a mirror model of the external world, and then in the brain, we observe the world like watching a movie  According to this view, inverted glasses will also invert the internal mirror model, and the brain generates visual perception according to this inverted mirror  However, more and more people began to question this explanation, and Degenna was one of them
The visual phenomenon he experienced on the 30th day of the experiment made him completely stand on the opposite of Cartesian mirror theory
Working principle of inverted glasses