Did you know that from google has a graph that charts the number of books that we bought in a certain category? In 1978, books on vision began to dramatically outperform other books. As a matter of fact, for over 30 years the sale of books about vision has grown by over 300%! However, in 2018, the graph hit the top of the curve and there is speculation as to whether it has plateaued or is on the decline.
