Remember the concept of nature's services from Chapter 1: conserving nature is absolutely necessary to the sustaining of meaningful life on Earth, its habitats and biodiversity, and its ability to continue to perform the services on which humanity and all life depends. Sustaining nature's services necessitates producing a minimal amount (“zero”) of damaging wastes and emissions. The Product Life Institute provides a worthwhile introduction to sustainability; see footnote. But how can we speak of zero waste or zero emissions if, as you learned earlier, no process is 100% efficient? The answer is that zero waste is a philosophy, one that says there is no waste: What we call “waste” or “pollutant” is really a useful resource. However, this philosophy recognizes that waste is now a major problem and, if we aspire to reduce waste 100%, we accomplish more than if our goal was 40% or 80%. Thinking of wastes and pollution in this manner is not contradictory to other concepts covered in this book such as pollution control and pollution prevention because humanity is working at a number of levels, both doing what we must at the present while also working toward the future vision of finding means to a sustainable environment and world.