A good illustration is [[water|H<sub>2</sub>O]], one atom of hydrogen and two atoms of oxygen. It can also take three forms: solid ice, liquid water, and floating clouds, steam, formless fog and invisible vapor, all of which are considered water. However, this [[analogy]] was historically taken too far as applied to God. The denial of the doctrine of the Trinity, as being in essence one Person only, not three divine Persons of One Being, was condemned as [[Monarchianism]] and as [[Modalism]] and as the [[heresy]] of Sabellianism<ref>[https://orthodoxwiki.org/Sabellianism '''Sabellianism''' (orthodoxwiki.org)]</ref>
An excellent [[Mathematics|mathematical]] illustration of the unity of the Trinity is the [[Geometry|geometrical]] form of the [[Triangle|triangular]] three-sided ''tetrahedron'', a [[Pyramid (geometry)|pyramidal]] construct of a single, indivisible point extending into three [[equilateral]] triangular faces simultaneously united to a single triangular base<ref>[https://www.mathsisfun.com/geometry/tetrahedron.html Solid geometry: tetrahedron(mathsisfun.com)]</ref>. This is especially evident when an equilateral tetrahedron is made of flawless transparent [[crystal]]. Through any one face of the crystal form each of the other sides is clearly visible. Each of the faces is a distinctly different face (they cannot be the same face) but all of them have exactly the same shape, the same size, and the same substance. What is predicated of any one of them is predicated of each of them. A tetrahedral crystal displayed standing on the flat surface of the jeweler's counter or the shelf of a display case cannot exist without three faces inseparably existing as extending from the single, undivided point of one apex to the same undivided triangular base at its base or foundation on which it stands: a single crystal, not three, with three faces, not one.
Also, for any solid physical object to exist, it must have