I was lucky, I think, that one of the bits of work we'd been doing gave a few clues. That was the work on trade. The work on obsidian which, as we were saying, gave you very concrete evidence allowing you to reconstruct trading systems from quite hard data, so that's one thing but then if you're asking why would cultures change, why would they develop, then the links that were taking placed between cultures were important but then the idea that began to build up was that it wasn't that, for instance, if we're talking about trade in the Aegean, the metal trade in the Aegean in the early Bronze Age, to talk about the Cyclades again. It wasn't the contacts with the Near East that were significant even though there may have been some, it was the fact that a trading system was building up from which a certain dynamic took - took off, really. And so this made me realise a little that one had to look at the relationships between the different processes that were going on, if you like, systems terminology, the different sub-systems of the culture system, and so if the trade was building up and we'd seen that through the obsidian and then the metallurgy in the Cyclades, if the trade was building up, what was happening to the social organisation and then how did this turn - tie in with the agriculture? And in my work in the Cyclades I'd naturally been interested in that and I came to realise, this was really after my dissertation was finished, the dissertation had a lot of emphasis on culture sequence and chronology, but thinking about culture process, you could see that, and the work at Sitagroi helped with this when we got all this information from Jane's work on the cereal crops and so on, that probably viticulture began in the Aegean and olive cultivation began in the Aegean. They weren't very easy to date but probably they began in the early Bronze Age and so maybe what was happening in the early Bronze Age, so-called, which sort of starts in the third millennium, starts shortly after 3000 BC, maybe what was happening was that trading links were building up, metallurgical practice was building up with new forms of weapons and new forms of drinking cups and so on, and wealth, for the first time, cumulative wealth for the first time, and this was the time also that new things were happening in agriculture. The development of viticulture which was giving you, obviously, grapes to eat but more particularly wine to drink, and it was clear that there were new shapes of drinking vessels and the whole business of drinking wine was clearly more than just nourishment, it was also something agreeable and potentially important. These days in archaeology one talks a lot about feasting which is much the same idea but it wasn't quite so explicitly stated then. And then the olive cultivation was important because in the Cycladic Islands which are a little bit arid, it's barley rather than wheat is the main cereal crop but you don't have great plains for cereals as you do in Thessaly or in Macedonia, rather you have the possibility for vineyards and olive groves and so on. And so I realised that the Mediterranean triad as it's called, that's cereals and vines and olives, was very important but probably became important at that time just as the early Bronze Age was taking off in the Cyclades. So I began to have the feeling that all these things were working together.