Sorry to throw a $50 word at you right at the beginning...
Trinity Sunday is months off...we still have to get through Epiphanytide, Lent, the Resurrection, Ascension, and Pentecost. In fact, it is the Sunday after Epiphany, the Baptism of the Lord, but please bear with me, they do have something to do with each other.
The accounts of Our Lord Jesus Christ's Baptism in the Jordan (today's selection for the Gospel at Mass may be found here). One non-believing professor I once had stated that, "Jesus' baptism must be a terrible embarrassment for Christians." I was puzzled then, and no less so now, why I should feel embarrassment. Indeed, this act, recorded pretty much similarly in all three Synoptic Gospels and alluded to in St. John's Gospel, demonstrates not only Jesus' adherence and obedience to the God of Israel in everything He said and did, but it demonstrates clearly how the perichoresis, the mutual indwelling, cooperation, and interplay of the three Persons of the Most Holy and Undivided Trinity works when one of the Persons is Incarnate in human form.
Take a moment for that to sink in. In fact, take all the time you need, just ponder it during that time.
We teach as we have received, that our One God has three Persons, whom we call the Father, the Son (or Word), and the Spirit. We teach as we have received that the Person of the Word took on an actual human body and actual human nature because of the love of this three-Personed God for us; it seemed good to all three that the Word would take this on. We teach as we have received that in this human body the Word united perfectly the Divine nature and being with the nature of human kind in the being of Jesus. This same Jesus, who had a highly unusual conception, unusual childhood, and uncanny grasp of the Israelite Scriptures and Tradition, showed His hand at this act of humility and obedience. The Word in human form was visited visibly by the Spirit Who loved and infused Him for eternity. The Word in human form was praised audibly by the Father Who loved and infused Him for eternity. The Word in human form accepted and let in the Persons Whom He loved and infused for eternity. Playing by the rules He had made, God the Holy Trinity showed us on the banks of the Jordan River the Divine Perichoresis, how God suffused human form, and how, if we turn to Him, He can suffuse us too with his cleansing and life-giving love.