I came across this sentence in a fictional dialog in my Latin lesson.
difficile est mihi hoc credere.
In this context,
hoc refers to someone else's claim of accomplishment. I had learned earlier that direct objects of
credere are normally expressed in the dative. But in the examples provided in my earlier lessons, the direct objects were people, not claims.
I looked this up in my Mac OS application version of Lewis and Short. The entry implied that the earlier usage of
credere was more common in business where it conveyed consignment of goods or money to another person. In this sense, where it meant "loan", "entrust", or "consign", the item of interest took the accusative while the person was expressed in the dative.
I'm guessing (L & S don't state this) that later, as
credere became used more generally to convey general trust, confidence, or faith, the accusative was dropped, but the person reference remained in the dative. However, believing things, still takes the accusative.
Does that sound like a good rule of thumb for using
credere properly? There is another credo dative thread on this exchange, but it is based on a more subtle example.