opportunity for keith haring is a blank poster. using chalk, the young man from pennsylvania draws a picture, a cartoon like drawing which he finishes in a minute or two and then moves on. he may do as many as 30 such drawings in a day. all different. but all the same in certain ways. he puts them down here so millions do. >> you don't have to know anything about art to appreciate it. there aren't any hidden secrets or things you are suppose to understand. he has got to be careful. technically what he is doing is illegal graffiti. haring doesn't think he is defacing anything. he believes it is art. many subway riders seem to agree. but the law is the law. for him, the arrest is short lived and worth the temporary humiliation for him because he wants ordinary people, subway riders to see his stuff. is it art? well, upstairs, that doesn't seem to be any question about it. he has done murals like this one on the bowery. often find haring working on paintings that look like for the world the subway drawings. this big one for all its si