Masson begins by asking if we ever know precisely what another person is actually feeling. It may be no harder, he argues, to discover the truth about feelings in dogs. Yet for all their evident loyalty, heroism and compassion, Masson highlights research which shows that dogs lie in a universe of scent a hundred million times more acutely appreciated than by man. It is a world of emotions readily available only to other dogs. To discover more about the complex but transparent nature of canine emotional responses, Masson acquired three large dogs to from a community with his own family and set about a close scrutiny of their feelings - the first, he says since Charles Darwin pointed us in the right direction 125 years ago.