If there is one thing that CEO Tim Cook doesn’t want people to know, it’s what dwells behind his company’s “signature.” As a result, most efforts to explain design at Apple end up reducing a complex 37-year history to bromides about simplicity, quality, and perfection–as if those were ambitions unique to Apple alone. So Fast Company set out to remedy that deficiency through an oral history of Apple’s design, a decoding of the signature as told by the people who helped create it. Catch up with the series so far: