Charles Hodge on Ephesians 5:9

V. 9. For the fruit of light,The common text has here πνεύματος instead of φωτός. The latter reading is now universally adopted as the correct one on the authority not only of the MSS. but of the context. i. e. the fruit or effect of divine illumination is in all, i. e. consists in all the forms of goodness, righteousness, and truth. Goodness, ἀγαθωσύνῃ, is that which makes a man ἀγαθός, good; and righteousness, δικαιοσύνη, is that which makes a man δίκαιος, righteous. These Greek words differ very much as the corresponding English terms do. Goodness is benevolence and beneficence; righteousness is adherence to the rule of right. Yet both are used for moral excellence in general. The evil and the good, included all classes of the vicious and the virtuous. Good works are works of any kind which are morally excellent. When however the words are contrasted as in Rom. 5, 7, or distinguished as in Rom. 7, 12, good means benevolent or beneficent; and righteous, just or upright. Goodness is that quality which adapts a thing to the end for which it was designed, and renders it serviceable. Hence we speak of a good tree, of good soil, as well as of a good man. Righteousness can properly be predicated only of persons or of what is susceptible of moral character; as it means conformity to law; or if predicated of the law itself, it means conformity to the nature of God, the ultimate standard of rectitude. Truth, here means religious or moral truth, or religion itself. The fruits of light, therefore, are all the forms of piety and virtue.