We all want to have an earth that lasts forever. Yet often we hear our parents say things about how different the earth was in the past ‘things were different in my day – the tomatoes tasted better’, or ‘in my day it was never this hot. What is happening to the world?’ Whilst our parents might be right (and I only say might!), this raises an important question – how do we pass onto our children, and their children, an earth that is at least as good as the one we have today, and how do we keep the earth in a good state of repair? The answer lies in two important concepts: the principles of intergenerational equity (IGE) and intragenerational equity (INGE). These are principles relating to the use of the earth’s renewable and non-renewable resources in this generation as well as future generations, and the impact of that use on present and future generations.