Two Triangles and a Circle. Since the two interwoven triangles alone are apt to be confused with the Shield of David, a circle is often used in combination with them, by weaving it through their six points. Thus the idea of eternity is added to the symbolism of the two triangles.
The Trefoil. A familiar Trinity emblem is that of the trefoil, with three lobes of equal size, yet one figure. It is a modification of the three interlaced circles which we have mentioned above.
The Trefoil and Triangle. A decorative figure is formed when the equilateral triangle and the trefoil are combined. It has been used frequently in stained glass, mural decoration and church embroidery.
The Trefoil and Three Points. Often one meets with a Trinity emblem composed of an equilateral triangle with a point projecting from the intersection of each arc with its neighbour. This is a modified form of the symbol just mentioned, and is made by combining a triangle with a trefoil, and then eliminating the lines within the trefoil. It is a very decorative figure.
The Triquetra. One of the finest of all the Trinity symbols is the triquetra. This mystical symbol is quite simple in form, yet full of meaning. The three equal arcs of the circle express the equality of the Three Divine Persons, their union expresses the unity of divine essence, their continuous form symbolizes eternity, and the fact that they are interwoven denotes the indivisibility of the Blessed Trinity. In the center of the triquetra is an equilateral triangle, the most ancient of the Trinity symbols, and each pair of arcs forms a vesica, the symbol of glory. Thus the one simple figure reminds us of many important truths.
The Triquetra and Circle. Somewhat less common, but equally good, is the combination of the triquetra and the circle of eternity. The circle is woven through the ends of the three-lobed figure, and results in a most decorative figure worthy of wider use.
The Triquetra and Triangle. A very fine symbol of the Holy Trinity is an interwoven triquetra and equilateral triangle. We reproduce one from the glass of Temple Church, in London. See symbol on the title page.
The Shield of the Trinity. If one examines closely the stained glass of the mediaeval churches, he will find examples of what is known as the Shield of the Blessed Trinity. A number of variations exist, but the simplest form is that of a figure with three curving sides, each exactly equal in length. At each angle is a small circle, and in the center is a larger circle. Bands connect the central circle with the outer ones. The smaller circles bear the words Pater, Filius, Spiritus Sanctus, (Father, Son, Holy Spirit). On each of the curving bands are the words non est meaning "is not." On the short diagonal bands are the words est, meaning "is."