Humankind has been consuming the natural resources, exhausting them, also discharging much quantities of waste matter, destroying the natural environment, and polluting it by population growth and man's activities. This human pressure on the natural environment raises the environmental pressure on humankind which injures man's health or brings disadvantages on human life and activities. When the environmental pressure is raised more than some value, a negative feedback acts on humankind from the natural environment, so it lowers the human pressure. The natural environment has a restoring power which lowers the environmental pressure. If the human pressure is lower than the restoring power of the natural environment, the natural environment lowers the environmental pressure, so the natural environment is healthy. To keep off the ruin of humankind, we must lower the human pressure on the natural environment. So we must lower population growth and keep man's activities under the restoring power of the natural environment.We must also manage the development and the industrial activities properly to protect the natural resources and the environment from insignificant destruction. Furthermore, we must develop the technology to lower the human pressure.
