The publishing imprint through which Reinertsen published principles-of-product-development-flow (2009, ISBN 9781935401001). The name "Celeritas" — Latin for "speed" or "swiftness" — reflects Reinertsen's central preoccupation with the economics of speed in product development. By self-publishing his magnum opus, Reinertsen retained full control over the content and format of his most important work, which features 175 numbered principles and extensive mathematical and economic reasoning. The book's distinctive orange cover and dense format became recognizable in the lean/agile community.