Heh is the fifth letter and has the value five. Sefer Yetzirah places it among the letters of the throat, with Alef, Chet and Ayin. The Talmud describes its shape precisely: it resembles an akhsadra, an open portico, and its foot is suspended, detached from the roof, leaving a small opening above. Careful scribes, says Rav Ashi, draw this suspended foot.
In Sefer Yetzirah, Heh is the first of the twelve simples. The book gives the simples twelve foundations, from sight to sleep. For Heh, it writes that G-d "made the letter Heh reign and bound a crown to it," and through it formed Taleh, the Ram, in the world, the month of Nisan in the year and the right hand in the body. The book also says that G-d chose three letters from among the simples, Yod, Heh and Vav, set them in His great Name and sealed with them the six directions of space.
In tractate Shabbat, after the lesson of Gimel and Dalet, the children read: "Heh Vav, this is the Name of the Holy One, blessed be He." These two letters appear in the divine Name. Placed in the middle of the reading, between the duty to give to the poor and the promise that follows, they recall before Whom this duty is fulfilled.
Tractate Menachot reads the verse "these are the generations of heaven and earth, behibaram," when they were created, as be-heh bera'am: He created them through Heh. Why was this world created through Heh? "Because it resembles a portico: whoever wants to leave, leaves." And why is its foot suspended? "For if he returns in teshuvah, he is brought in" through the upper opening. Why not come back in the way he left? Because that would not suffice; Resh Lakish teaches that one who comes to purify himself is helped. The Alphabet of Rabbi Akiva takes up this reading: Heh is the Name of the Holy One, blessed be He, through which the whole world was created.
Five, the open door. Heh is both one of the three letters that seal space, in Sefer Yetzirah, and a letter of the Name, for the children of Shabbat 104a. The Talmud reads in its shape that of this world: the freedom to leave is real, and another door, higher up, remains open for returning.