Another general classification of Terms divides them into the following two respective classes; (1) Concrete Terms; and (2) Abstract Terms. A _Concrete Term_ is a term denoting either a definite object, person or thing which is subject to perception and experience, and may be considered as actually existent concretely, as for instance: horse; man; mountain; dollar; knife; table; etc., or else an attribute thought of and used solely as an attribute, as for instance: "beautiful, wise, noble, virtuous, good," etc. An _Abstract Term_ is a term denoting the attribute, quality or property _considered as apart from the object, person or thing_ and as having an abstract existence, as for instance: "beauty; wisdom; nobility; goodness; virtue," etc. As we have seen elsewhere, these qualities have no real existence _in themselves_, but are known and thought of only in connection with concrete objects, persons and things. Thus we cannot know "Beauty," but may know _beautiful things_; we cannot know "Virtue," but we may know virtuous people, etc. An _attribute or quality_ is _concrete_ when expressed as an _adjective_; and _abstract_ when expressed as a _noun_; as for instance, "beautiful" and "beauty," respectively, or "virtuous" and "virtue," respectively. The distinction may be summed up as follows: A Concrete Term is _the name of a thing or of a quality of a thing expressed as an adjective and as merely a quality_; while an Abstract Term is the name of a quality of a thing, _expressed as a noun and as a "thing" in itself_. Certain terms may be used as either Concrete Terms or as Abstract Terms, and certain authorities have seen fit to classify them as _Mixed Terms_, as for instance the terms: "government; religion; philosophy;" etc. Another general classification of Terms divides them into two respective classes as follows: (1) _Positive Terms_; and (2) _Negative Terms_. A _Positive Term_ is a term which denotes its own qualities, as for instance: "good, human, large, square, black, strong," etc. These terms indicate the presence of the quality denoted by the term itself.