1 This Psalm is entitled, “For the winepresses.” And, as you observed with me, my beloved (for I saw that you attended most closely), nothing is said in its text either of any press, or wine-basket, or vat, or of any of the instruments or the building of a winepress; nothing of this kind did we hear read; so that it is no easy question what is the meaning of this title inscribed upon it, “for the winepresses.” For certainly, if after the title it mentioned anything about such things as I enumerated, carnal persons might have believed that it was a song concerning those visible wine-presses; but as it has this title, yet says nothing afterwards of those winepresses which we know so well, I cannot doubt that there are other wine-presses, which the Spirit of God intended us to look for and to understand here.
Therefore, let us recall to mind what takes place in these visible winepresses, and see how this takes place spiritually in the Church. The grape hangs on the vines, and the olive on its trees. For it is for these two fruits that presses are usually made ready; and as long as they hang on their boughs, they seem to enjoy free air; and neither is the grape wine, nor the olive oil, before they are pressed. Thus it is with men whom God predestined before the world to be conformed to the image of His only-begotten Son, who has been first and especially pressed in His Passion, as the great Cluster.
Men of this kind, therefore, before they draw near to the service of God, enjoy in the world a kind of delicious liberty, like hanging grapes or olives: but as it is said, “My son, when you draw near to the service of God, stand in judgment and fear, and make your soul ready for temptation:” so each, as he draws near to the service of God, finds that he has come to the winepress; he shall undergo tribulation, shall be crushed, shall be pressed, not that he may perish in this world, but that he may flow down into the storehouses of God.
He has the coverings of carnal desires stripped off from him, like grape-skins: for this has taken place in him in carnal desires, of which the Apostle speaks, “Put ye off the old man, and put on the new man.” All this is not done but by pressure: therefore the Churches of God of this time are called winepresses.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)