I'm a bit confused by the way you've phrased this. Specifically, the bit about "why they were considered so noble." When historians speak of nobility, it is not generally moral or ethical virtue they're talking about, but high social and economic status. So if I said "John did a noble thing by saving that baby from the fire," that's not at all the same thing as saying "John is a noble because he comes from a powerful family of rural landowners."