God the Trinity is not a frozen entity, not something static or lifeless. On the contrary, within the Trinity there is the plenitude of life and love. ‘God is love’, says St. John the Theologian (1 John 4:8; 4:16). Yet there can be no love without the beloved. A lonely, isolated monad can love only itself: self-love is not love. An egocentric unit is not a personality. As the human person cannot experience his personhood save through communion with other persons, so in God there can be no personal being save through love for another personal being. God the Trinity is the plenitude of love, each hypostatic Person exists in a relationship of love for the other Persons.
The Trinity is therefore a relational entity. The relations between the three Persons are relations between ‘I’ and ‘Thou’, or ‘I’ and ‘He’. ‘Thou, Father, art in Me, and I in Thee’, says Christ (John 17:21). Concerning the Holy Spirit, our Lord says, ‘All that the Father has is Mine; therefore I said that he will take what is Mine and declare it to you’ (John 16:15). We read in St. John’s Gospel: ‘In the beginning was the Word, and the Word was with God’ (John 1:1). The Greek text actually says ‘and the Word was towards God’ (pros ton Theon). This underscores the personal nature of the relationship between God the Word and God the Father: the Son is not only born from the Father, He not only exists with the Father, He is turned towards the Father. Thus each Hypostasis in the Trinity is turned towards the other Hypostases.
The icon of the Holy Trinity by St. Andrei Rublev portrays three angels sitting at a table upon which is a Cup, the symbol of Christ’s redemptive sacrifice; the three Persons of the Trinity turn simultaneously to each other and to the Cup. The icon has captured the divine love which reigns within the Trinity. The greatest manifestation of this love was the incarnation of the Son of God for the redemption of humanity. Orthodox Tradition regards Christ’s saving sacrifice as a common act of love and self-emptying of all three Persons of the Trinity. It is in this sacrifice that the love which exists within the Trinity was given and became known to humans. As St. Philaret of Moscow said, it is the ‘crucifying love of the Father, the crucified love of the Son, and the love of the Holy Spirit triumphing through the power of the Cross’.