Complex sentence: A cornucopian is someone who disdains the notion that there are natural limits to growth, and instead believes our planet can hold an endless number of human beings and provide a limitless abundance of natural resources.
Split into simpler sentences: A cornucopian is someone who disdains the notion that there are natural limits to growth, and instead believes in an endlessly abundant future. They believe that our planet can hold an endless number of human beings and provide a limitless abundance of natural resources.