2. The writers were diverse, yet David was principal. The five other authors. The Psalms לאסף, were they written by Asaph? Jeduthun, Korah, Assir, Elkanah, Abiasaph, why are their names set before certain Psalms? The Psalms ἀνεπίγραφοι, without inscription.
The writers of the Psalms were undoubtedly diverse, although Saint Augustine in his City of God, Book VII, section 14, Euthymius Monachus Zigabenus in his Preface to the Psalms, Rabbi Ibn Ezra of the Hebrews, and others assert that all were written by one David. That particular one is undoubtedly the King and Prophet David, that נָעִים זְמִרוֹת יִשְׂרָאֵל, sweet Psalmist of Israel, 2 Samuel 23:1, because he was not only the πρῶτος λαβὼν τὸ πνεῦμα τοῦ ψάλλειν παρὰ τοῦ Θεοῦ, πρῶτός τε συνέθηκε καὶ ἔγραψε ψαλμοὺς, first to receive the Spirit of psalming from God, and the first to write and compose Psalms, as Athanasius says in his Synopsi: but also because he composed the greatest part of them, partly in exile, while fleeing Saul and his son Absalom; partly at home, while tranquil and quiet. Whence they are called the Psalms of David. Besides David, five Authors are mentioned, Moses in Psalm 90, Solomon in Psalm 127, Heman the Ezrahite (perhaps the grandson of Samuel, 1 Chronices 25:1; 2 Chronicles 5:12) in Psalm 88, Ethan the Ezrahite in Psalm 89, and Asaph (a prophet, 1 Chronicles 25:2) in Psalms 50; 73-83. Although concerning the Psalms of this Asaph, especially those that are inscribed לְאָסָף, of Asaph, some are in doubt as to whether they were written by Asaph, or were committed to him or to his posterity. But, since some of the Psalms of David are also inscribed לְדָוִד, for David, or of David; and Psalms 96, 105, and 106 are said to have been delivered into the hand of Asaph, yet are not inscribed לְאָסָף, of Asaph: it is probable that this expression indicates the Author. But the names of Jeduthun, and of three sons of Korah, Assir, Elkanah, and Abiasaph, are set before certain Psalms, not that they were composed by them, but because they were committed to them for singing. Moreover, there are twenty-five Psalms ἀνεπίγραφοι, without inscription, of author or title: that most of them were also composed by David, as none of use doubt it, so we do not more curiously inquire concerning their writers, thus judging with Gregory the Great in de libro Jobi: When we, who are inquiring concerning a writer, acknowledge the substance, what else are we doing, except, while reading the letters, busying ourselves concerning the pen? With Jerome in his Prologue to Malachi we would not dare to say: What Psalms have not titles, we say that they belong to those with whose names the prior Psalms were prefaced.
 Euthymius Zigabenus (late eleventh, early twelfth century) was a Greek monk of the order of St. Basil.  See 1 Chronicles 16.  See Psalms 42; 44-49; 84; 85; 87; 89  See Exodus 6:24; 1 Chronicles 6:22, 23.