I pondered that sentence for a while as well, stu. As far as I can understand it, "modern" means since Galileo and the claim appears to be that they didn't subscribe to his theory before it was written. That is, I think we will all agree, not too surprising. But that is the nature of learning anything. You work within the way you understand the world until find out something new and then you have to change what you thought. As st Paul said "when I was a child I thought like a child... Now I am a man I have put aside childish things". That applies to society as much as individuals in my view.