What did David Hume mean by matters of fact?

For the Scottish philosopher David Hume, "matters of fact" represent one of the two primary categories of human knowledge, the other being "relations of ideas."1

Unlike relations of ideas, which can be determined through rational inspection and logical deduction, matters of fact are known exclusively through experience. Hume characterized matters of fact as follows:12

• Empirical Nature: They are derived from data of sensation or internal consciousness, which Hume termed impressions.2
• Logical Independence: Matters of fact reveal no inherent logical relations; they are "logically barren," meaning their properties and connections must be accepted as they are given.2
• Contradictory Possibility: Because they are not based on logical necessity, the contradictory of any matter of fact is always conceivable. For instance, while it is a fact that fire burns, it is logically possible to conceive of a world where it does not.2
• Causality: The most significant matters of fact involve causality, such as the claim that "fire causes heat." Hume argued that we cannot observe a "necessary connection" between events, but rather a habitual association formed in the mind through repeated experience.12