In the early 1960s Italian design legend Bruno Munari published his visual case studies on shapes: , , and, a decade later, . Using examples from ancient Greece and Egypt, as well as works by Buckminster Fuller, Le Corbusier, and Alvar Aalto, Munari invests the three shapes with specific qualities: the circle relates to the divine, the square signifies safety and enclosure, and the triangle provides a key connective form for designers. One of the great designers of the twentieth century, Munari contributed to the fields of painting, sculpture, design, and photography while teaching throughout his seventy-year career. After World War II he began to focus on book design, creating children's books known for their simplicity and playfulness.