Sacred Geometry is such an intriguing lore. The more I study it, the more inspiration it brings. Let me share a bit of the ancient, mysterious teaching...

In general, whenever one is to construct a certain geometric shape, it is essential to create the first dot or the central point, which can be extended either into a line or a curve. In Sacred Geometry, lines are considered masculine and curves feminine shapes and that is where the game of endlessly attracting opposites begins. It is the most basic principle of life, innate to everything, including the micro cosmos of the atoms or the macro cosmos of the solar systems. Protons and electrons attract each other and form atoms, that later attract each other and construct molecular systems, in the same way the sun attracts the planets and the planets attract the moons. 
However, without the initial central point, the magnetic principle that attracts both the opposing energies, there would be no shape and no motion. Metaphorically, one could say that the central point is the source of all creation. The Big Bang theory, in fact, is also based on the thought that the universe spread out of the hot density of a single point.  

In geometry, from the central point one can construct a perfectly enclosed unified shape – the circle. Aristotle wrote in the Physica that the circle is “the perfect, first, most beautiful form” and indeed both the common and the sacred geometry consider circle to be the original shape, one that symbolises the unity, because as it further becomes apparent, all the other shapes, forms and tokens originate from this very shape. It being the circle in the two dimensional or the sphere in the three dimensional, circular shapes are present in the most fundamental forms of life such as atoms and molecules, seeds or eggs, but also the planets, moons and stars, spreading all the way to the gigantic circular galaxy shapes in the universe.
The circle also represents the cycles of life and thus is connected to growth and movement. The cyclical movement patterns are essential to life and can be observed between all the planets circling around the sun, the moons circling around the planets and the planets circling around their axis, which transmits to the cycles of days, months and years.

Interestingly enough, Pythagoras, who has established Sacred Geometry teachings in Ancient Greece, was already aware that the Earth has a spherical shape. He also preceded the claims of modern cosmologists that everything in the universe is of spherical origin. However, as mentioned above, whenever one is to draw a circle, or any other geometric shape, he first needs to start with the central point and then use a compass to draw a circle around it. And so whereas the central point symbolised the original oneness, the circle already resembles oneness made of duality, because two points that create a ratio construct it. And this very principle of duality beholds the potential to create furthermore shapes. If a second circle is drawn in the ratio between the initial point and the perimeter of the original circle, the two circles create the mystical Vesica Piscis.

Vesica Piscis was given a symbolic name “the womb of the universe” because all the other shapes emanate from it.

Vesica Piscis can be found in various natural forms including human body parts such as ears, eyes, mouth, nostrils, vagina and etc. Also the pinecone shaped pineal gland has this shape, which produces serotonin, a derivative melatonin, a hormone that affects the wake/sleep patterns and seasonal functions, but is also considered the mystical third eye among some.

The French philosopher, mathematician, and writer René Descartes, who was dedicated to the study of the pineal gland, called it the “principal seed of the soul” and interestingly, most seeds do have either a circular or a pinecone shape and so do the  eggs. Moreover, all embryos are shaped this way at the developing stage and importantly, animals and humans both tend to curl up in a spherical shape when seeking protection. Thus, all the original shapes of living forms spring from the primal shapes of the circle and Vesica PiscisUsing the Vesica Piscis, straight lines and curves, one can construct a triangle, a perfect square and then continue with more complicated geometric shapes such as rectangle, pentagon, hexagon and all the other platonic solids.
Furthermore, if we continue drawing overlapping circles, in which the centre of each is the circumference of the other surrounding circles of the same diameter, we will soon get The Seed of Life and The Flower of Life. These figures form a flower-like pattern and have been used, along with the Vesica Piscis, as one of the main decorative motifs since ancient times. The Seed of Life creates numerous geometric and symbolic shapes such as the cross, the triangle, the hexagon and the six-pointed star (also called the Star of David) and has also been observed in the creation of human fetus as well as in the molecular systems. The six circles around the central one in the Seed of Life are considered a metaphor for the Bible’s six days of God’s creation.

If we continue drawing twelve to nineteen overlapping circles around the central one, we get The Flower of Life, the well known Sacred Geometry pattern, used in various cultures as an important token which symbolises the year's cycle, which is also correlated to the zodiac and the house system in astrology. In The Flower of Life one can also observe various symbols such as the Yin and Yang, the Runes, the Sephirotic Tree of Life or the mysterious Fruit of Life.

Then if we interconnect all the central points in The Fruit of Life pattern by using straight lines, the Metatron’s Cube is derived. Within The Metatron’s Cube, one can observe many different geometric shapes and forms, including the five Platonic Solids. The Platonic Solids can be found in the periodic table of elements, but it has also been observed that all crystals have their atoms arranged in these three dimensional shapes. However, the most mysterious shapes in The Platonic Solids are the Dodecahedron, which consists of pentagons, pentagrams and the Double Tetrahedron, which consists of hexagons and hexagrams. In ancient Greece the Dodecahedron was considered the most mysterious of the five Platonic Solids and its secret wasn’t allowed to be brought into light for the public, for it concealed the biggest mysteries of the Universe. The Dodecahedron also holds the key to the Golden Mean, another important Sacred Geometry term. The Golden Mean or The Golden Section translates to the sacred proportional system found in nature and is widely used in the Arts. Curiously enough, it has also been scientifically proven that both the pentagon and dodecahedron and the hexagon and double tetrahedron can be found in the chemical structural shapes of human DNA. And moreover, scientists recently revealed a study, which concludes that the whole universe may in fact be in the shape of a Dodecahedron.

The Tree of Life (above) and Runes (below) in the Flower of Life symbol.


The Yin and Yang within the Flower of Life

Vesica Piscis in Gothic architecture

The Fruit of Life in the Flower of Life symbol

Metatron's Cube

Pentagon and Dodecahedron (the Pentagram symbol)
and Hexagon and Double Tectahedron (the Hexagram symbol) in human DNA

Molecules arrangement