@freemo Original source - so it's actually describing practical limitations of human senses https://books.google.co.uk/books?id=ZqiiwZ7zJPsC&pg=PA9&dq=%22Human+experience+of+space+and+time+in+the+physical+world.%22&hl=en&newbks=1&newbks_redir=0&sa=X&redir_esc=y#v=onepage&q=%22Human%20experience%20of%20space%20and%20time%20in%20the%20physical%20world.%22&f=false