4 “You have understood my thoughts from afar; You have tracked out my path and my limit”; “and all my ways You have seen beforehand”. What is, “from afar”? While I am yet in my pilgrimage, before I reach that, my true country, You have known my thoughts....The younger son went into a far country. After his toil and suffering and tribulation and want, he thought on his father, and desired to return, and said, “I will arise, and go to my father.” “I will arise,” said he, for before he had sat.
Here then you may recognise him saying, “You have known my down-sitting and up-rising.” I sat, in want; I arose, in longing for Your Bread. “You have understood my thoughts from afar.” For far indeed had I gone; but where is not He whom I had left? Wherefore the Lord says in the Gospel, that his father met him as he was coming. Truly; for “he had understood his thoughts from afar.” “My path,” he says; what, but a bad path, the path he had walked to leave his father?...What is, “my path”?
That by which I have gone. What is, “my limit”? That whereunto I have reached. “You have tracked out my path and my limit.” That limit of mine, far distant as it was, was not far from Your eyes. Far had I gone, and yet You were there. “And all my ways You have seen beforehand.” He said not, “hast seen,” but, “hast seen beforehand.” Before I went by them, before I walked in them, You saw them beforehand; and You permitted me in toil to go my own ways, that, if I desired not to toil, I might return into Your ways. “For there is no deceit in my tongue.” What meant he by this? Lo, I confess to You, I have walked in my own way, I have become far from You, I have departed from You, with whom it was well with me, and to my good it was ill with me without You....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)