"Earth you are, and to earth you will return," were G-d's words to Adam, the first human being (Genesis 3:19). In the words of King Solomon, "And the earth returns to the land as it was, and the spirit returns to G-d, who gave it" (Ecclesiastes 12:7). The next stage in the continuing saga of a human life is that the body should return to the earth, the source of all physical life, and be reunited with it, just as the soul returns to its divine root.
Indeed, these two "returns" are coupled. The earth is the source of physical life because G-d's essence resides within it in a deeply hidden but profoundly real way. The
natural decomposition of the body into the earth allows the expeditious return of the soul to its source.
It is therefore of utmost importance to preserve the integrity of the body, and to allow the burial to occur as soon as possible. The in-between state is most difficult for the soul, as it has no body with which to relate to our world, and neither is it free of its tenuous bonds to our world to see things from the purely spiritual perspective.
The body's "returning to the earth" is directly commensurate with the soul's ability to return to the
supernal Source from which it is drawn.
Interment in the earth is also integral to the process of the techiat ha-meitim, the future resurrection of the dead. As the first human being was initially formed from the earth, so, too, when the dead are brought back to life in the World to Come, their bodies will be re-formed from the earth
in which they have been interred.
Two important steps precede the actual burial: a) the Taharah ("purification"); b) the funeral (called the Levayah).
The Taharah is a ritual cleansing process in which the body is cleaned and groomed, and water is ritually poured over it. In life, water is the source of all our nourishment; spiritually, too, water also has this unique property. At various stages in our lifetime (e.g., before marriage, after giving birth), we immerse in a mikveh to achieve ritual purity; so, too, is the body ritually purified in preparation for this next phase of its existence. With the taharah we acknowledge with dignity the life that resonated within this body and still leaves its trace on it --forever. After the purification, the deceased is dressed in special white clothes (called tachrichim), signifying purity and holiness.
On the most basic level, the Levayah ("accompaniment"--the funeral procession), in which we accompany the body to its resting place, is a show of respect to the deceased. The Hebrew word levayah also indicates "joining" and "bonding." Even as we mourn a soul's departure from manifest connection with our own physical existence, we understand that what binds our souls together--the fundamental Divine essence that all souls share--is far more powerful than the changes wrought by death. We and the deceased remain bonded--living souls all. By participating in the levayah we provide comfort to the soul as it undergoes this very difficult transition from one life to another, as the presence of our souls emphasizes the bonds that transcend this change.