8 Therefore Solomon also, hinting at this grace, says in Ecclesiastes, Come hither, eat your bread with joy (that is, the spiritual bread; Come hither, he calls with the call to salvation and blessing), and drink your wine with a merry heart (that is, the spiritual wine); and let oil be poured out upon your head you see he alludes even to the mystic Chrism); and let your garments be always white, for the Lord is well pleased with your works; for before you came to Baptism, your works were vanity of vanities. But now, having put off your old garments, and put on those which are spiritually white, you must be continually robed in white: of course we mean not this, that you are always to wear white raiment; but you must be clad in the garments that are truly white and shining and spiritual, that you may say with the blessed Esaias, My soul shall be joyful in my God; for He has clothed me with a garment of salvation, and put a robe of gladness around me.
Source: Catechetical Lectures (New Advent)