ד (or Dalet, Daled) The fourth letter of the Hebrew alphabet, ד Daleth symbolizes "a door." When adapted to Greek, it became the letter Delta (a triangle).
Daleth is related with:
The four elements of the physical world: fire, air, water, and earth
The four states of the matter: solid, liquid, gaseous, combustion
The four atoms in Alchemy: hydrogen, carbon, nitrogen, oxygen
The four worlds of Kabbalah: Atziluth, Briah, Yetzirah, and Assiah
The four letters of the name of God: Iod, Hei, Vau, Hei
Etc
In Kabbalah, the letter Daleth represents a youth, the terrestrial man, who receives charity from his heavenly man, his letter Gimel. For this, Shaddai El Chai must stand at the open door (Daleth) of the entrance of his house (physical body).
