The point, which can hardly be repeated too often, is that differentiation is not separation. The head and the feet are different, but not separate, and though man is not connected to the universe by exactly the same physical relation as branch to tree or feet to head, he is nonetheless connected - and by physical relations of fascinating complexity.
Why are people so afraid? The answer is that they have made themselves helpless and dependent on others. We are so lazy, we do not want to do anything ourselves. We want a Personal God, a Savior or a Prophet to do everything for us.