The author considers the title of its last chapter ambiguous, offering "summum bonum" as one possible meaning.  
The first chapter of this work considers three possible meanings of the sentence "The definition of horse is 'A hoofed quadruped of the genus Equus.'" The author considers the title of its last chapter ambiguous, offering "summum bonum" as one possible meaning.  The second chapter criticizes Herbert Spencer, saying he is not so much an evolutionist as a hedonist, while the third chapter adopts the term "intuition" from Henry Sidgwick, who had an important influence on the author of this work.  The author says it is an "open question" whether that which is normal is good, thus criticizing the "naturalistic fallacy."  FTP, identify this 1903 work, the magnum opus of G.E. Moore.
The first chapter of this work considers three possible meanings of the sentence "The definition of horse is 'A hoofed quadruped of the genus Equus.'
{Principia Ethica}