Johns painted recognizable things so people couldn't comment on what they thought they saw but rather, the painting itself. His work was revered by John Cage and the two were good friends and collaborators for the Merce Cunningham Dance Company. Cage's writing about Johns' work is so perfect and so understanding that it is the closest the written word has ever been able to describe the visual and conceptual meaning to any art ever. Read about it here.
Jasper Johns (with thread painted flag):