Besides the argument that the exchange-correlation hole is much more localized than the exchange hole, other possible ways to understand the interesting point made in contribution (2.4.10) about fitting exchange on atoms and getting correlation in molecules could be: (i) The exchange energy functional (and the exchange hole) changes linearly under uniform coordinate scaling. The correlation energy (and hole), by contrast, does not exhibit any simple scaling. However, when the electron-electron interaction becomes dominant with respect to the kinetic energy (see contributions (2.4.5) and (4.5.8)), then the exchange-correlation energy scales again as the exchange energy. It might thus make sense to have an exchange-like functional to capture (at least part of the) static (left-right) correlation. (ii) More recent work by Burke, Perdew and coworkers (see ref. 179 for a recent review) has clarified the sense in which LDA is a universal limit for coulombically bound systems, with exchange as the leading term.