2 If any of the holy children who praise the Name of the Lord were to ask of me and say to me, “for evermore” I understand to mean unto all eternity: but why “from this,” and why is not the Name of the Lord blessed before this, and before all ages? I will answer the infant, who asks not in contumacy. Unto you it is said, masters and children, unto you it is said, “Praise the Name of the Lord; blessed be the Name of the Lord:” let the Name of the Lord be blessed, “from this,” that is, from the moment ye speak these words. For you begin to praise, but praise ye without end....Or, since in this passage he seems to signify rather humility than childhood, the contrary of which is the vain and false greatness of pride; and for this reason none but children praise the Lord, since the proud know not how to praise Him; let old age be childlike, and your childhood like old age; that is, that neither may your wisdom be with pride, nor your humility without wisdom, that you may “praise the Lord from this for evermore.” Wherever the Church of Christ is diffused in her childlike saints, “Praise ye the Name of the Lord;” that is, “from the rising up of the sun unto the going down of the same.”
3. “The Lord is high above all heathen”. The heathen are men: what wonder if the Lord be above all men? They see with their eyes those whom they worship high above themselves to shine in heaven, the sun and moon and stars, creatures which they serve while they neglect the Creator. But not only “is the Lord high above all heathen;” but “His glory” also “is above the heavens.” The heavens look up unto Him above themselves; and the humble have Him together with them, who do not worship the heavens instead of Him, though placed in the flesh beneath the heavens.
4. “Who is like the Lord our God, that has His dwelling so high; and yet beholds the humble?”. Any one would think that He dwells in the lofty heavens, whence He may behold the humble things on earth; but “He beholds the humble things that are in heaven and earth”: what then is His high dwelling, whence He beholds the humble things that are in heaven and earth? Are the humble things He beholds His own high dwelling itself? For He thus exalts the humble, so as not to make them proud. He therefore both dwells in those whom He raises high, and makes them heaven for Himself, that is, His own abode; and by seeing them not proud, but constantly subject to Himself, He beholds even in heaven itself these very humble things, in whom raised on high He dwells. For the Spirit thus speaks through Isaiah: “Thus says the Highest that dwells on high, that inhabites eternity; the Lord Most High, dwelling in the holy.” He has expounded what He meant by dwelling on high, by the more full expression, “dwelling in the holy.”...
Source: The Enarrations, or Expositions, on the Psalms (New Advent)