It is my firm belief that not only do we all need nature, but we all seek nature, whether we know we are doing so or not.But despite this, our children are growing up nature-deprived (丧失). I spent my boyhood climbing trees. These days, children are robbed of these ancient freedoms, due to problems like crime, traffic, the loss of the open spaces and strange new ideas about what is best for children, that is to say, things that can be bought, rather than things that can be found.The truth is to be found elsewhere.A study in the US: families had moved to better housing and the children were assessed for ADHD (多动症). Those whose housing had more natural views showed an improvement of 19%； those who had the same improvement in material surroundings but no nice view improved just 4%.A study in Sweden indicated that kindergarten children who could play in a natural environment had less illness and greater physical ability than children used only to a normal playground. A US study suggested that when a school gave children access to a natural environment, the entire school would do better in studies.Another study found that children play differently in a natural environment. In playgrounds,children create a hierarchy (等级) based on physical abilities, with the tough ones taking the lead.But when a grassy area was planted with bushes, the children got much more into fantasy play, and the social hierarchy was now based on imagination and creativity.Most bullying (恃强凌弱) is found in schools where there is a tarmac (柏油碎石) play- ground； the least bullying is in a natural area that the children are encouraged to explore. This reminds me unpleasantly of Sunnyhill School, with its hard tarmac, where I used to hang about in corners dreaming about wildlife.But children are frequently discouraged from involvement with natural spaces, for health and safety reasons, for fear that they might get dirty or that they might cause damage. So, instead, the damage is done to the children themselves: not to their bodies but to their souls.One of the great problems of modern childhood is ADHD, now increasingly and expensively treated with drugs. Yet one study after another indicates that contact with nature gives huge benefits to ADHD children.However, we spend money on drugs rather than on green places.The life of old people is much better when they have access to nature.The most important for the growing population of old people is in quality rather than quantity of years. And study after study finds that a garden is the single most important thing in finding that quality.In wider and more difficult areas of life, there is evidence to indicate that natural surroundings improve all kinds of things. Even problems with crime and aggressive behaviour are reduced when there is contact with the natural world.Dr William Bird, researcher from the Royal Society for the Protection of Birds, states in his study, "A natural environment can reduce violent behaviour because its process helps reduce anger and behavior that people might regret later." Wild places need encouraging for this reason, no matter how small their contribution.We tend to think human beings are doing nature some kind of favour when we are protecting nature.The error here is far too deep : not only do humans need nature for themselves, but the very i-dea that humanity and the natural world are separable things is damaging.Human beings are a species of animals.For seven million years we lived on the planet as part of nature.So we miss the natural world and long for contact with non-human life.Anyone who has patted a dog, stroked a cat, sat under a tree with a glass of beer, given or received a bunch of flowers or chosen to walk through the park on a nice day, understands that.We need the wild world. It is necessary to our well-being, our health, our happiness. Without other living things around us we are less than human. What is the author's firm belief? A． People seek nature in different ways. B． People should spend most of their lives in the wild. C． People have quite different ideas of nature. D． People must make more efforts to study nature.

A． People seek nature in different ways.
B． People should spend most of their lives in the wild.
C． People have quite different ideas of nature.
D． People must make more efforts to study nature.