Darden also emphasized mechanisms as an important framework concept in scientific discovery (Darden 1980, 1982, 1986, 1991). In the discovery of protein synthesis (jointly investigated by molecular biologists and biochemists in the 1950s and 1960s), scientists didn’t simply have an “A-ha” moment. Rather, they deployed strategies for revealing how a mechanism works (Darden 2006; Craver and Darden 2013). Darden characterizes the process of mechanism discovery as an “extended, piecemeal process with hypotheses undergoing iterative refinement”; that process occurs via the construction, evaluation, and revision of mechanism schemas in light of observational and experimental constraints (Darden 2006: 272).