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 daily life on Coenties Slip.
Indiana's journal page for April 8, 1962, includes a small sketch of a ginkgo leaf, with the artist noting "ginkgos are noticeably in bud now, their new greenery [making] a definite tracery in Jeannette [Park]."
Indiana discusses his return to constructions, specifically Marine Works, deciding to finish it "once and for all," and Four, bringing them "into focus with his current direction." Next to his sketch of Four Indiana comments that he added the Gothic four to the lower three circles and the word four to the bottom of the construction, all in white gesso. He also records the work's medium (iron, gesso, and oil on wood), its dimensions (96 x 21 1/4 inches), and that he signed it in stencil on the reverse (Robert Indiana / New York / 1959–1962). Also illustrated on the page are the letters "M" and "W" of Marine Works.