L'algebra
Raffaele Bombelli's L'algebra, printed in Bologna by Giovanni Rossi in 1579, is an early algebra textbook for practical mathematicians and students. The four diagrams are geometric proofs drawn as labelled rectangles, squares, and a cuboid with lettered corners, with numbers such as 32 and 20 written inside the shapes. A designer could take from them the clean, schematic grammar of letter-labelled construction drawings, with lines, corner letters, and boxed numerals.
