Robert Indiana kept a series of illustrated journals during the late 1950s and 1960s, in which he discusses the development of his work as well as his daily life on Coenties Slip.

Indiana's journal page for February 7, 1962, includes a sketch of Polygon: Pentagon, with a note that the work is "in tribute [to] an old friend." A note added at a later date indicates that the friend is Particci, one of Indiana's cats. 

Indiana records reluctantly returning to Scarsdale (where he taught art classes) for the beginning of the spring term, but that the classes had improved, and the day ended up being one of the most pleasant ones there. He then writes that upon his return to the city he went to dinner with J. (his partner, fashion designer John Kloss) and Art (psychologist and art collector Arthur Carr), and that Kloss had found Sidney Tillim's "Month in Review" article (in Arts Magazine, reviewing Recent Acquisitions: Painting and Sculpture at the Museum of Modern Art, New York.) Indiana describes it as a "[very] acrid blast," made more "indigestible" by his applause of Claes Oldenburg, an old exhibition mate and fellow Chicagoan. He goes on to say that his "sunken spirits were a little buoyed by Steve's [Durkee] and Gene's [Swenson] remarks. Steve noted [that] Tillim was a hardhead bastard from way back; and Gene dismissed it completely."

He also records that Swenson had not been working on an article that he was planning, but that hopefully the displeasure of Tillim's article would spur him on. He notes that "sign painter" as a name was discussed, and that he had a "foreboding about [this]."