. It is a representation
of the common clover, or shamrock, as the Irish call it. The legend of
the conversion of Ireland says that St. Patrick was preaching on the
hillside, and wishing to illustrate from nature the sublime doctrine of
the Trinity to his pagan hearers, he bent down and plucked a piece of
shamrock at his feet, and held it up to show how what was three, in one
sense, might be one in another.

[Illustration: Trefoil]

The unity of the Persons in the one Godhead is sometimes represented by
intersected triangles, or by the trefoil placed under a triangle.

The truth of the Trinity is also suggested by any {64} threefold
arrangement in the various forms of the ornamentation.

The figure known as the _triquetra_, made by the interlacing of three
portions of circles, is also symbolical of the Holy Trinity. This is a
very ancient emblem, and is found with frequency upon the stone crosses
erected in the early days of Christianity in Great Britain. It is
sometimes used in ornamentation of the dress of our Lord or of the
Evangelists.

[Illustration: Intersected triangles. Trefoil placed under a triangle.
Trequetra.]

From the thirteenth century we have the symbol of the equal and
interlacing _Circles_. "The three equal circles symbolize the equality
of the three Persons in the Trinity, the binding together in one figure
the essential unity, while the circular form signifies a
never-beginning, never-ending eternity." The word _trinitas_, used in
this symbol, may itself {65} be divided into three syllables. One of
these syllables is placed in each circle; but they have no perfect
meaning, and will not form any word, unless united. In the space left
vacant by the intersection of the circles the word _unitas_ is placed.

[Illustration: Interlacing circles]

From the sixteenth century we have another device setting forth the
doctrine of the Trinity. This is a triangle terminating at the corners
in three circles, and in the center another circle with lines
connecting it with the circles at the corners. A legend is combined
with the figure, which serves to explain it. The English equivalent of
the Latin words is as follows: _Deus_, God; _Pater_, the Father; {66}
_Filius_, the Son; _Sanctus Spiritus_, the Holy Ghost; _est_, is; _non
est_, is not.

[Illustration: Triangle and circles]

_Symbols of the father Almighty._--For the first four centuries the
only symbol employed to represent God the Fath