Caring is a response to the variety of features of moral situations: need, harm, past promises, role relationships etc. In the case of need, our obligation to respond in an appropriately caring way arises when we are able to respond to need. We can roughly distinguish needs here from desires by describing a need as something that is basic for our survival and our ability to have a minimally decent life. Desires, on the other hand, are for things we merely want. Humans need some things for their very survival: food, clothing, shelter,and health care are examples here. There are also other things that we need for a minimally decent life. Aristotle cites friendship; Mill cites liberty and Rawls offers self-esteem as a need in this sense. Still, there is no universal, cross-cultural understanding of need. Rather, need is mediated by a number of factors including family, culture, economic class, gender and sexuality, disability and illness. Finally, as we respond to needs, we should recognize the vast differences in power that exist.