St. Thomas Aquinas's Commentary on Wedding Feast of Cana

"'Cana' means 'zeal' and 'Galilee' means 'passage.' So this marriage was celebrated in the zeal of a passage, to suggest that those persons are most worthy of union with Christ who, burning with the zeal of a conscientious devotion, pass over from the state of guilt to the grace of the Church. 'Pass over to me, all who desire me' (Sir 24:26). And they pass from death to life, i.e., from the state of mortality and misery to the state of immortality and glory: 'I make all things new' (Rv 21:5) [....]

"[Christ] serves good wine first who begins to live in a saintly and spiritual manner at the start of his conversion, but later sinks into a carnal life: 'Are you so foolish as, having begun in the Spirit, to end in the flesh?' (Gal 3:3). 

"Christ, however, does not serve the good wine first, for at the outset he proposes things that are bitter and hard: 'Narrow is the way that leads to life' (Mt 7:14). Yet the more progress a person makes in his faith and teaching, the more pleasant it becomes and he becomes aware of a greater sweetness: 'I will lead You by the path of justice, and when you walk you will not be hindered' (Prv 4:11). Likewise, all those who desire to live conscientiously in Christ suffer bitterness and troubles in this world: 'You will weep and mourn' (below 16:20). But later they will experience delights and joys. So he goes on: 'but your sorrow will be turned into joy.' 'I consider that the sufferings of this present time are not worthy to be compared with the glory to come, which will be revealed in us,' as is said in Romans (8:18)."

St. Thomas Aquinas, Commentary on the Gospel of St. John, ch. 2, lecture 1, nos. 338, 363 (John 2: 1, 10); http://dhspriory.org/thomas/english/John2.htm