What is ironic about the subject Ichabod likes to read about?

In , Ichabod Crane is esteemed for his
erudition by the local women for he had read several books quite through. This in itself is
ironic as the urbane, well-read Irving satirizes the simple, easily-impressed rural people.
Ichabods favorite book, however, of which he is said to be a complete master, is Cotton Mathers
History of New England Witchcraft. Ichabods continual study of this volume
is ironic firstly in view of his own superstitious and fearful nature, as he must be continually
terrifying himself. Indeed, it almost seems as though this is his object, since it is his habit
to read these direful tales in the gathering dusk:

Then,
as he wended his way to the farmhouse where he happened to be quartered, every sound of nature,
the boding cry of the tree toad, the dreary hooting of the screech owl, fluttered his excited
imagination.

It is also ironic that the schoolmaster,
charged with bringing education and enlightenment to Sleepy Hollow, chooses as his favored
reading material a compendium of superstitious tales rather than a more rigorous academic work.
Mather himself left a legacy of scientific discourses, including his work on inoculation, as
well as sermons and theological writing, but it is his work on witchcraft, essentially a book of
childish stories, that Ichabod reads over and over again.