What it is
Aleph (א) is the first letter of the Hebrew alphabet. In modern Hebrew it is silent — a placeholder for a vowel sound — but its name and written form derive from the Proto-Sinaitic pictograph of an ox-head, and its numerical value is one. The Greek letter alpha and the Latin letter A are its descendants.
In Hebrew Scripture
The first word of the Hebrew Bible — Bereshit (בְּרֵאשִׁית, "In the beginning") — does not begin with aleph. It begins with bet. The aleph's near-absence from the opening of Scripture has been noticed and discussed in Jewish commentary for centuries. The midrashic tradition gathered in Genesis Rabbah offers several explanations: that bet opens the word baruch ("blessed") while aleph opens arur ("cursed"); that bet's numerical value of two represents the duality proper to a created world; and — most often quoted — that the aleph was assigned a more honored place later, opening the first commandment at Sinai with Anokhi ("I am the Lord your God").
In Jewish mystical tradition
Aleph carries unusual weight in the Jewish mystical tradition. In the Sefer Yetzirah (an ancient cosmological text) and in later Kabbalistic and Chasidic writings, the silent first letter is read as a symbol of the unutterable Divine Unity that precedes all created speech — the letter from which all other letters, and so all created things, derive. The interpretive details differ from text to text and teacher to teacher, but the general picture of aleph as the letter of Divine origin is consistent across the tradition.
In Christian-Hebrew-letter usage
The aleph appears in Christian contexts as a way of evoking the Hebrew foundation of Scripture — the Old Testament heritage that the New Testament and the Latter-day Saint Standard Works both build on. Used with care for the original tradition, the borrowing is respectful and common.
Why it's the SumBible mark for the Old Testament
The Old Testament is Hebrew Scripture. Marking it with the Hebrew first letter — rather than with a Christian symbol — honors the OT as Scripture in its own right, before any later Christian or Christological interpretation reaches back to it. The aleph signals that what follows is rooted in the Hebrew tradition from which the Christian and Latter-day Saint canons descend.
Sources
- Brown-Driver-Briggs and HALOT, the standard Hebrew lexicons, for the linguistic content (form, numerical value, derivation).
- Genesis Rabbah 1:10 (and surrounding sections) — the midrashic discussion of why the Torah opens with bet rather than aleph.
- General Jewish mystical references (the Sefer Yetzirah and the Zohar) for the broader tradition of aleph as the letter of Divine Unity; readers interested in this body of thought are best served by primary editions with scholarly introductions rather than secondary summaries.