The way depth gets compressed in the retinal image is the same as in a photograph: parallel lines that recede into the distance converge at a vanishing point on the horizon.   This geometrical relationship is called linear perspective  https://smarthistory.org/how-one-point-linear-perspective-works/.  Although there are some hints of linear perspective in Greek and Roman art, linear perspective was not accurately described until the Renaissance. Brunelleschi https://www.youtube.com/watch?v=bkNMM8uiMww is credited with discovering the rules of linear perspective. 

discussion topic consider:  If the linear perspective is what we see, why did someone have to discover it? Use the above information to answer the discussion topic. (100-150 words) just use those 2 links information and use 1st subject to write. And pls use your own word