There is a Torah obligation to wear tefillin upon one’s arm and head each day. The tefillin contain four parashiyot, or sections of the Humash, which the Torah commands us to bind upon our arms and heads. The Torah presents this command four times, in each of the four sections contained in the tefillin (Shemot 13:9, 16; Devarim 6:8, 11:18).

The Sefer Ha’hinuch (421) provides a most insightful explanation for the reason underlying this mitzvah:

A person, being a physical being, will naturally be drawn after desires, for this is the nature of physical matter — to seek everything that benefits it . . . And the Almighty wanted to bring us, His sacred nation, merit, and [therefore] commanded us to establish powerful guards around us, meaning, we are commanded that words of Torah shall never leave our mouths day or night, and that we shall place four fringes on the corners of our garments, a mezuza on our doorway, and tefillin upon our arms and heads. This is all to remind us, so that we withhold our hands from wrongdoing and not stray after our eyes and the evil thoughts of our hearts.

The tefillin thus serve as a reminder that we must strive for something far more meaningful than physical pleasures and de-lights. Like the tzitzit on our garments and the mezuzot on our doorways, the tefillin direct our attention to our spiritual mission, reminding us that we are to strive to serve the Almighty by studying Torah and performing mitzvot, rather than spending our lives in the endless pursuit of physical gratification.

Why were specifically these four sections of the Torah chosen to be placed upon our arms and heads?

The Sefer Ha’hinuch explains that these four sections contain the basic, fundamental concepts upon which the Jewish religion is based:

• קבלת עול מלכות שמים (the acceptance of Divine Kingship);
• 'אחדות ה (the belief that God is One);
• יציאת מצרים (the Exodus from Egypt, which proves God’s unlimited might and providence over the earth).

  As these constitute the fundamental principles of Judaism, the Torah required tying them near one’s brain and heart — the organs that are commonly seen as the seats of human intellect. This mitzvah is thus intended to reinforce our belief in, and keen awareness of, these tenets, thus reminding us of our obligations toward God. 

Scholars have offered symbolic interpretations of a number of details concerning the tefillin. The work Hen Tov (cited in Yalkut Yitzhak, 423) comments that the four compartments of the tefillin shel rosh allude to a person’s two eyes and two ears, which must be subjugated to the service of God. The tefillin shel rosh thus reminds us to avoid looking upon forbidden sights and listening to forbidden sounds. The single compartment of the tefillin shel yad, the Hen Tov suggests, symbolizes the single heart in a person, which sustains and controls all the body’s organs. Just as in the shel yad the four sections are combined into a single compartment, so must a person bring together all aspects of his being for the single goal of serving his Creator.

A slightly different approach is taken by the Elyah Rabbah, who explained that the tefillin represent the five senses. The four compartments of the tefillin shel rosh correspond to the four senses that are controlled in the head — hearing, sight, smell and taste — whereas the single compartment of the tefillin shel yad parallels the sense of touch, which occurs in the hand. The tefillin thus instruct that every area of our conduct, everything we do with our physical bodies, should be geared towards the service of the Almighty.

Thus, wearing tefillin is much more than merely a mechanical act, or a simple ritual. Rather, it serves to remind us of the fundamental precepts of the Jewish faith, and, perhaps most importantly of all, of the need to direct our lives toward spiritual excellence, rather than confining ourselves to a purely physical existence.