The fifth Johnsonian principle is Structure and Rationality – structural clarity in planning. The Central Library’s Johnson Building is organized into a nine-section or nine-square grid. In the image above, the “A” section is the entrance to the building facing Boylston Street and the “B” section is where the children’s room is currently located. The letters are used simply to identify each section of the nine-square grid.
Johnson’s words about structure and rationality include: “(At BPL) I kept the nine squares as the expression and did not try to put a façade on it. In other words, the nine squares were represented in all three facades.”