 Carroll does not elaborate on these issues, but this passage contains the central message: Simple models prevent our theories from having a “black-box” character, meaning that they will not simply be a recipe for calculating without giving any physical insight. Carroll claims that simple models are necessary in order to expose the mechanisms by which chemical phenomena come about. High-level theoretical calculations are not capable of showing us these mechanistic relationships, even though they are based on the quantum mechanical principles that describe the fundamental physics of the system. Or, as Hoffmann puts the point: “[I]f understanding is sought, simpler models, not necessarily the best in predicting all observables in detail, will have value. Such models may highlight the important causes and channels” (Hoffmann, Minkin, &amp; Carpenter 1996).