I use the terms 'Excellence' and 'Perfection' to denote the same ultimate end regarded in somewhat different aspects: meaning by either an ideal complex of mental qualities, of which we admire and approve the manifestation in human life : but using `Perfection' to denote the ideal as such, while `Excellence' denotes such partial realisation of or approximation to the ideal as we actually find in human experience.

ME Book 1 Chapter 1 Section 4