The reason can only be this: heroic poetry depends on an heroic age and an age is heroic because of what it is not because of what it does.

The balance of private good and general welfare is at the bottom of civilized morals but the morals of the Heroic Age are founded on individuality and on nothing else.

The Border Ballads for instance and the Robin Hood Ballads clearly suppose a state of society which is nothing but a very circumscribed and not very important heroic age.