A 2024 JACS paper presented a potential-of-mean-force (PMF) study that failed to locate the famed tetrahedral intermediate in the mechanism of aminolysis of esters (amine + ester → amide + alcohol), causing the authors to question the existence of the intermediate. The resolution of the problem is a fascinating foray into pH-dependent kinetics, the effect of pH on free-energy surfaces (FES) of reactions, and the delicate issue of presenting microsteps (e.g. proton-transfer) in chemical mechanisms. The talk will start with the 1968 Blackburn-Jencks mechanism and rate law, with a fresh presentation showing the four pH regions resulting from kinetics studies (the evidence for an intermediate). How this information should affect FES profiles (and the issue of microsteps) is then presented. Finally, the issues surrounding PMF representations of FES profiles are presented. Improved understanding of how PMF profiles relate to FES profiles will aid in the application of molecular dynamics simulation to mechanism elucidation.