Dolphins have the power to make people feel better just by their presence, according to a leading marine biologist. 'I cannot explain it in scientific terms but, without any doubt, everyone who sees them in the wild is lifted by them,' Jonathan Gordon, of Oxford University Zoology Department, said. 'You only ever see them in the wild if they want you to see them. They are the only wild animal that comes to man of their own free will and that makes you feel privileged. You get a buzz because they are joyful, and you can prove scientifically that they spend a lot of their life playing.' Professor Gordon works for the International Fund for Animal Welfare and spends months on the organization's research boat. 'If things aren't going well on the boat and you are depressed, the sight of dolphins lifts you and makes you feel better at once. They cannot be doing this on purpose, but I can believe that people who are intensely depressed or suffering from some kind of mental blockage could be eased by swimming among them.' 'I cannot go along with those who claim they have magical powers but even though I am scientifically hardheaded I have to admit they somehow make you feel good.' That view is shared by the authors of Beyond the Blue, a book on the healing power of dolphins. The authors say that when the mind is calm it triggers the release of a chemical also found in the anti-depressant drug Valium. Jenny Sheridan, of the Royal College of Speech and Language Therapists, said, 'Swimming with dolphins will not repair any brain damage. But if the child is suffering from lack of confidence it might help.' Mark Simmonds of the Whale and Dolphin Conservation Society, said, 'The interaction of dolphin with sick children can be instrumental in recovery. No one can explain why. But the behavior. of these beautiful animals induces awe and pleasure in children.' This passage is mainly about ______.