“This is how the Book of Zohar explains the holiness of the Hebrew alphabet, and this is not an allegory, but the essence of the subject: all the letters that we see in the Torah are manifestations of 22 streams of the spiritual Light of the higher worlds. These transcendent streams of Light transmit their radiance to the letters that communicate the holiness of the Torah itself, the holiness of the Torah scroll, tefillin, mezuzah and all the Holy Scriptures. And in accordance with the attitude towards holiness with which they are written, the influence and energy of the flows of divine Light on the letters themselves increase. Therefore, a Torah scroll, in which there is one non-kosher letter, is completely unsuitable, because the spiritual Light is not transmitted through it, as it should, when the Torah scroll is read by people.

From "Path to the Tree of Life" by Rabbi Moshe-Chaim Luzzat​to (1707-1747)​​​​

Professional suitability
According to Jewish Tradition, writing, checking and selling sacred scrolls can only be trusted to an honest person. Only a deeply religious and observant adult Jew (from the age of 13) who can read Hebrew can become a sofer. Sofer is a male profession.

​​Canons of writing sacred texts

Letters
The Hebrew alphabet consists of 22 basic and 5 additional letters. There is no division into uppercase and lowercase letters. The type of letters in sacred scrolls is determined by strict canons. The laws, rules and traditions of writing texts are recorded by the rabbis in extensive literature. The canons of writing letters do not take into account the size of the font used.

Texting technique
Kosher letters of the sacred text are obtained only by writing and by no other means: neither by engraving, nor by application, nor by printing.

The invisible part of the soyfer​'s work​
In order for holiness to descend into what a sofer writes, he must first of all direct his thought to it. First, it concerns the scrolls themselves, which must be written to fulfill the respective commandments of the Torah or the sages. To do this, the sofer says: “I am writing for the holiness of the Torah scroll / tefillin / mezuzah.” Secondly, it concerns the "names" of God. To do this, the sofer says: "I am writing for the holiness of the name of God." If he forgot to consecrate what was written at least mentally (or even doubts that he consecrated), then this invisible flaw cannot be corrected. No test can reveal such a marriage. The customer or buyer can only rely on the piety of the sofer.

The integrity of the letter and its background
Each letter must be intact, without any cracks. A crack visible to the naked eye makes the entire letter non-kosher, and with it the entire manuscript.
The letters should not touch each other or the edge of the parchment.
The contact between the letters makes the entire scroll non-kosher, that is, unsuitable for its intended use - the fulfillment of the commandment.

Letter order
In tefillin and mezuzah, the letters are written strictly in the order of reading the text - from right to left. According to this rule, a missing letter cannot be entered after the fact. There is no such restriction in the Torah scroll and the Esther scroll.

Error correction
There are errors that are allowed to be corrected, and there are those that are not allowed to be corrected. In turn, the rules and techniques for correcting errors are strictly regulated. The main time of the sofer's training is devoted not to the calligraphic development of the alphabet, but to the diagnosis of writing anomalies and their correction.

Writing technique
The order of writing the elements of each letter is not regulated. The most optimal approach is used when each element is written from left to right - in the direction of the parchment pile.
Sacred texts are not written from memory, but copied. A sofer first reads each Bible verse aloud, then writes it.
Each word is written as a whole and is not broken up for hyphenation.
Punctuation marks are not included. In order to get the edge of the text even, certain letters can be stretched.

Manuscript Checking System: Traditions and the Use of Modern Technologies
Each manuscript must pass several rigorous checks on the visible part of the sofer's work:

• checking the integrity of the parchment

• the presence of a line

• ink color and quality

• line alignment left and right

• correct formatting of paragraphs

• grammar check of the entire text, including spaces between words

• spell check of each word, including missing, extra and erroneous letters

• graphical analysis of each letter, including cracks in letters, spikes and crowns, touches within letters and between letters, spikes and crowns

In addition to these traditional checks, computerized testing has also been practiced and proven to be effective. The translation of a scanned scroll into a text format with the help of specially developed programs makes it possible to identify missing, superfluous and erroneous letters that have eluded the expert.