Metaphysics is also linked to the world of parapsychogy, (e.g.) the investigation of telepathy. Similar in nature, some like to use the words interchangeably, but metaphysics takes it own shape and form. Supernatural happenings and miracles merge with metaphysics, as well, and are usually classified under the subject.
In Hume's "Enquiry Concerning Human Nature," he seeks to bring insight to the masses regarding the absurdity of religious belief. Hume uncovers a lack of evidence associated with fervent religious belief and contends that wise individuals have the sense to separate themselves from partaking in this passionate faith. The foundation that Hume's argument rests upon is that no causal relationship can be inferred from one experience to another. Mankind can only predict the future with a degree of certainty based on past experiences, although they can never be absolutely sure that X will always follow Y, even if in the past this has been the case.