This psalm was put first as a preface to all the rest, as a powerful persuasive to the serious study of the whole book, and of the rest of the holy scripture, taken from that blessedness which attends upon the study and practice of it. It shews us, the holiness and happiness of a good man, ver. 1-3 The sinfulness and misery of a wicked man, ver. 4, 5. The ground and reason of both, ver. 6.