Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn.
Putting into words the reality of unreality and the unreality of our reality is near impossible.
It is why R’lyehian is sacred to us - it transcends the medium that we use to communicate in ways much deeper than cognitive understanding can perceive.
R’lyehian is the language of the Old Ones.
As it is not meant for the common tongue it is often described as very guttural and inhuman when heard aloud. This is because it is merely the closest that the human vocal apparatus can come to reproducing these syllables borne of an ancient language.
The inhuman quality of the language lends to the sound a deep resonance that echoes not only through our body in powerful vibrations but across the cosmos, through all space time realities.
The potency is dependent on the skill of the practitioner and so practice is essential to using the language to continue the Work and reach Ascension.
It is for this reason that the language is sacred to us.
Though there are many phrases,
"ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn"
chanted by the Cult of Cthulhu
is the most famous.