Why does everybody call God by four letters? The Hebrews by the four vowels "he ho ha hi"; the Egyptians by "Theuth"; the Persians by "Syre"; the Magi by "Orsi"; whence "Oromasis"; the Greeks by "Theos"; ourselves by "Deus"; the Arabs by "Alla"; Mahomet by "Abgdi." Again, we accept "Jesu" from Gabriel... Surely, such diverse races would not otherwise have agreed on the one name of the unknown God, unless they were divinely inspired? And if they received it from Adam, it was by divine inspiration they received that name rather than others.
The Hebrews say that, if pronounced correctly, all miracles can be wrought in that name- which is the most difficult thing of all to do; it takes a miracle alone to pronounce it.... God puts all things in order by means of four: essence, being, power, action. Celestial things He orders by means of four sets of three, sub-celestial things by means of the four elements. Accordingly, He wanted to be represented by four letters.
-Marsilio Ficino. The Philebus Commentary. translated by Michael J.B. Allen.