1....When ye hear sung in the Psalms, “Praise the Lord, you children”; imagine not that that exhortation pertains not unto you, because having already passed the youth of the body, you are either blooming in the prime of manhood, or growing gray with the honours of old age: for unto all of you the Apostle says, “Brethren, be not children in understanding; howbeit, in malice be children, but in understanding be men.” What malice in particular, save pride? For it is pride that, presuming in false greatness, suffers not man to walk along the narrow path, and to enter by the narrow gate; but the child easily enters through the narrow entrance; and thus no man, save as a child, enters into the kingdom of heaven. “Praise the Name of the Lord.”...Let Him therefore be always proclaimed: “Blessed be the Name of the Lord, from this time forth for evermore”. Let Him be proclaimed everywhere: “From the rising up of the sun unto the going down of the same, praise ye the Name of the Lord”.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)