After Pentecost, it is fitting that we celebrate the Holy Trinity.
I find it helpful to study this icon and then let the Spirit speak to me.
The subject of The Trinity received various interpretations at different time periods, but by the 19th-20th century the consensus among scholars was the following: the three angels who visited Abraham represented the Christian Trinity, "one God in three persons" – the Father, the Son (Jesus Christ), and the Holy Spirit. Art critics believe that Andrei Rublev's icon was created in accordance with this concept. In his effort to uncover the doctrine of the Trinity, Rublev abandoned most of the traditional plot elements which were typically included in the paintings of the Abraham and Sarah's Hospitality story. He did not paint Abraham, Sarah, the scene of calf's slaughter, nor did he give any details on the meal. The angels were depicted as talking, not eating. "The gestures of angels, smooth and restrained, demonstrate the sublime nature of their conversation". The silent communion of the three angels is the centre of the composition.
In Rublev's icon, the form that most clearly represents the idea of the consubstantiality of the Trinity's three hypostases is a circle. It is the foundation of the composition. At the same time, the angels are not inserted into the circle, but create it instead, thus our eyes can't stop at any of the three figures and rather dwell inside this limited space. The impactful center of the composition is the cup with the calf's head. It hints at the crucifixion sacrifice and serves as the reminder of the Eucharist (the left and the right angels' figures make a silhouette that resembles a cup). Around the cup, which is placed on the table, the silent dialogue of gestures takes place.The left angel symbolizes God the Father. He blesses the cup, yet his hand is painted in a distance, as if he passes the cup to the central angel. Viktor Lazarev suggests that the central angel represents Jesus Christ, who in turn blesses the cup as well and accepts it with a bow as if saying "My Father, if it is possible, may this cup be taken from me. Yet not as I will, but as you will". (Mt 26:39) The nature of each of the three hypostases is revealed through their symbolic attributes, i.e. the house, the tree, and the mountain. The starting point of the divine administration is the creative Will of God, therefore Rublev places the Abraham's house above the corresponding angel's head. The Oak of Mamre can be interpreted as the tree of life, and it serves as a reminder of the Jesus's death on the cross and his subsequent resurrection, which opened the way to eternal life. The Oak is located in the centre, above the angel who symbolizes Jesus. Finally, the mountain is a symbol of the spiritual ascent, which mankind accomplishes with the help of the Holy Spirit. The unity of the Trinity's three hypostases expresses unity and love between all things: "That they may all be one, just as you, Father, are in me, and I in you, that they also may be in us, so that the world may believe that you have sent me." (John 17:21)
The wings of two angels, the Father and the Son, interlap. The blue colour of the Son's robe symbolizes divinity, the brown colour represents earth, his humanity, and the gold speaks of kingship of God. The wings of the Holy Spirit do not touch the Son's wings, they are imperceptibly divided by the Son's spear. The blue colour of the Holy Spirit's robe symbolizes divinity, the green colour represents new life. The poses and the inclinations of the Holy Spirit and the Son's heads demonstrate their submission to the Father, yet their placement on the thrones at the same level symbolizes equality.