The Physics of Berkeley's Day

Before the scientific revolution, it was possible to hold onto a common sense picture where you encounter things the way they really are. This pushed conscious experience back inside the head and said it's just something generated by the brain. Berkeley quite rightly said that if our starting point in forming our beliefs, our opinions about how the world is, is just blobs of sensation, then how can we so much as form the idea of an object independent of us? And his answer was, you can't, it's just an illusion.