It belongs to the lore of computer science that Claude Shannon's master's thesis (1937) revolutionized the design of (relay) switching circuit design. However, as often is the case when taking a closer look at the historical records, things were slightly more complex. Neither was Shannon's paper an isolated result in switching theory, nor was it immediately absorbed into the engineers' daily practice. It proved to be only usable in a small number of situations and had to be used in conjunction with other techniques and the engineer's know-how. Boolean algebra would only become more important and more generally useful once standard situations were created.