All of these things, energy maybe not so much - but time, attention and stress are fluid and situation matters. An individual mood even matters. There are times when I do want to get there by walking, because I want to take longer, because I have the time and that's more relaxing. So, I'm actually getting something back. I'm gaining from an expenditure. Why would I pay all this money, go across town, rush to sit in my seat and listen to a piano concert for an hour and a half? Because I'm getting something from it and I'm getting more than I gave. These trade offs are actually important and we're doing them all the time, explicitly and inexplicitly. I would say that what a culture or a society emphasises is a way of characterizing its preference for certain kinds of living, early kinds of living. Café society, siesta time, not rushing dinner, all of these are indications of a particular fluidity. Which maybe we're losing with al the technology and the constant awe and all that kind of thing. The focus on this and the ability to be aware of it, I think, also improves product design. Because if I have a product that's a delight to use and takes a little longer, but is easy to remember, that's going to be preferential to its opposite. You can actually do a kind of comparison, but it's very subjective. Putting this awareness in the mind of designers is very fulfilling.