Sustain:
 
To keep in existence without diminishing, to provide sustenance and nourishment

• A sustainable community:
   
  
  • Nourishes, allowing all its members to flourish
     
    
  • Is able to continue indefinitely
     
    
  • Does not mean "no change" or "never changing" or "status quo"
     
    
  • Does not mean utopia

Sustain means to keep in existence without diminishing, to nourish. It means operating in such a way that a community doesn't use up all its resources. Notice that sustain does not mean to keep the status quo--it does not mean that nothing ever changes.

It also doesn't mean utopia. It doesn't mean that bad things never happen. There will always be floods and hurricanes. Some businesses may fail, some people will go hungry. Sustainability means that we continually work to make things better and we make sure that the systems we set up are helping rather than harming the process.