Feast of the Holy Trinity- a collation

Interlaced Triquetra symbol inside an equilateral triangle which is interlaced with a circle (i.e. pseudo-Celtic knotwork or interlaced ribbons). Could be used as a Christian Trinitarian decorative/ornamental symbolic element, but might also be open to other interpretations.

For other versions of the triquetra, see also Image:Triquetra-Vesica.png , Image:Triquetra-Vesica-solid.png , Image:Triquetra-tightly-knotted.png , Image:Triquetra-Double.png , and Image:Triquetra-circle-interlaced.png .
AnonMoos [Public domain]
Also see Triquetra-circle-interlaced.png
Trefoil and Triangle outline

Symbols of the Trinity: Equilateral Triange; Circle of Eternity; Three interwoven Circles; Triangle in Circle; Circle within Triangle; Interwoven Circle and Triangle; Two Triangles interwoven in shape of Star of David; Two Triangles in shape of Star of David interwoven with Circle; Trefoil; Trefoil and Triangle; Trefoil with points; Triquetra; Triquetra and circle; Shield of the Holy Trinity; Three Fishes linked together in shape of a triangle; Cross and Triangle overlapping; Fleur de Lys; St. Patrick’s Shamrock.

Feast of the Holy Trinity, also called Trinity Sundayfeast in honour of the Trinity. It is celebrated in the Christian churches on the Sunday following Pentecost (the 50th day after Easter). It is known that the feast was celebrated on this day from as early as the 9th century. Celebration of the feast gradually spread in the churches of northern Europe, and in 1334 Pope John XXII approved it for the entire church. In the liturgical Church Year, Anglican and Lutheran churches date the Sundays that follow Trinity “after Trinity”; the Roman liturgy dates these Sundays “after Pentecost.” ..[..] Feast of the Holy Trinity Britannica .com

The feast of the Blessed Trinity was introduced in the ninth century and was only inserted in the general calendar of the Church in the fourteenth century by Pope John XXII. But the cultus of the Trinity is, of course, to be found throughout the liturgy. Constantly the Church causes us to praise and adore the thrice-holy God who has so shown His mercy towards us and has given us to share in His life.

Click here for commentary on the readings in the Extraordinary Form of the Roman Rite.

This is the fundamental dogma, on which everything in Christianity is based, is a mystery in whose name all Christians are baptized. The feast of the Blessed Trinity needs to be understood and celebrated as a prolongation of the mysteries of Christ and as the solemn expression of our faith in this triune life of the Divine Persons, to which we have been given access by Baptism and by the Redemption won for us by Christ. Only in heaven shall we properly understand what it means, in union with Christ, to share as sons in the very life of God.

Trinity Sunday
The dogma of faith which forms the object of the feast is this: There is one God and in this one God there are three Divine Persons; the Father is God, the Son is God, the Holy Spirit is God. Yet there are not three Gods, but one, eternal, […]

Solemnity of the most Holy Trinity Catholic Culture