Yes I agree, Keep_Calm, but on the other hand, I think I agree with her when she says that the best PhDs are small. Even if it is an ambitious topic, I think it's still possible to be focussed and direct about it. Some of the theses I have read as examples to help me with mine are so waffly and uncertain about what they are trying to say. Too much stuff can detract from the weight of argument rather than add to it. But of course, it is a lot easier to pontificate about this than it is to do it ...