Apollonius' Canon

Apollonius' Canon states states that two nouns in regimen are either both articular or both anarthrous. This pattern was observed by a second-century Greek grammarian Apollonius of Dyscolus. In other words, where there is a noun phrase with two nouns, a head noun and another noun in the genitive case which qualifies it, then both nouns will either have the article or both nouns will not have the article. There is no difference in the meaning of the expression whether the article is there or not. Thus ὁ λόγος τοῦ θεοῦ means the same as λόγος θεοῦ.

Apollonius' Canon is usually discussed in relation to the genitive because of the two nouns, the qualifying noun is usually in the genitive.