The Door.

"Dalet (ד) is the door, דלת, (delet). Very few people know that they know about the Dalet. Even fewer open it, for they are afraid to go inside. "

-Lawrence Kushner

-The Book of Letters, a Mystical Alef-bait

Here am I.

While everyone can say, "I am present", only a very few can say, הנני, "Here am I". For to answer הנני means that you no longer belong only to yourself. To answer הנני means that you gave the Hay, ה, of your being over to the One who calls. That is why Hay is the letter most often linked with G-d's name. 

-Lawrence Kushner

-The Book of Letters, a Mystical Alef-bait

.image here, it says 'Elohim' which is the plural form of God. Hay is the middle letter of the word.