How much do we need?

I was idly wondering earlier if I would be able to live off a part time salary. I didn't think particularly deeply about it - it was a fleeting thought, but it gave way to another thought - how much do we need?

I mean, if we have enough money for a home, food, a car if we don't live close enough to walk where we need to go - do we need any money after that? Do we need all the stuff we buy ourselves? If we see something we like in the shop but we don't buy it for ourselves, is our life really affected by that, or have we forgotten about it by the next day? How much do our possessions really matter, and how much "stuff" do we need to be happy? So many questions to ask ourselves!