what's the meaning of the following sentences? Here deduction often ends and dreams of utopia begin, for it seems that most of us find it hard to think of the human race developing into a race of angels. All in all, as a theory of history, the above view has had many eminent supporters.

问题补充:

If one holds this theory, one feels that modern man must be more intelligent and civilized today than his ancestors, as well as physically and morally superior to them. One further assumes that this progress will continue into an ever more glorious future. Here deduction often ends and dreams of utopia begin, for it seems that most of us find it hard to think of the human race developing into a race of angels. All in all, as a theory of history, the above view has had many eminent supporters.