7 Also the blessed David shall advise you the meaning of this, saying, You have prepared a table before me in the presence of them that afflict me. What he says, is to this effect: Before Your coming, the evil spirits prepared a table for men, polluted and defiled and full of devilish influence; but since Your coming. O Lord, You have prepared a table before me. When the man says to God, You have prepared before me a table, what other does he indicate but that mystical and spiritual Table, which God has prepared for us over against, that is, contrary and in opposition to the evil spirits? And very truly; for that had communion with devils, but this, with God. You have anointed my head with oil. With oil He anointed your head upon your forehead, for the seal which you have of God; that you may be made the engraving of the signet, Holiness unto God. And your cup intoxicates me, as very strong. You see that cup here spoken of, which Jesus took in His hands, and gave thanks, and said, This is My blood, which is shed for many for the remission of sins.
Source: Catechetical Lectures (New Advent)