Definition of PR

Here's how Scott M. Cutlip, Allen H. Center and Glen M. Broom defined PR in "Effective Public Relations" back in 1978. Does this definition still apply? This book has been reprinted mulitple times with the same defintion. Should we re-examine it? What definition do you stand by?

"Public relations is a management function that establishes and maintains mutually beneficial relationships between an organization and the publics on whom its success or failure depends."