In Parshas Re’eh, the Torah outlines certain acts of mourning that were practiced by the non-Jews in those times. Some would make cuts in their body, whilst others would tear out hair between their eyes. The Torah forbids such actions, saying: “You are children of G-d, do not cut yourselves, nor tear out hair between your eyes over a death.” Similarly, in Parshas Kedoshim, the Torah tells us: “You should not make any cuttings in your flesh for the dead, nor print any marks upon you; I am Hashem.” These mitzvos teach that it is wrong to make a cut in one's body as a sign of mourning. In contrast, there is a positive commandment to tear one's clothing on the occasion of the death of a close relative (this is known as kriah). The Shulchan Aruch states: “Someone whose relative has died, (if it is a relative that one is required to mourn over), must tear [their garment] for them.” It is striking how very similar actions of tearing are regarded so differently in Jewish law, to the extent that cutting one's flesh is forbidden and yet, tearing one's clothing is obligatory?
In order to understand the difference between cutting one's body and cutting one's clothing, it is necessary to analyze the first event in the Torah in which clothing plays a role – that of the chet (sin) of Adam Harishon. The Torah tells us that before the chet, Adam and Chava did not wear any clothes, yet they felt no shame. However, after they ate from the fruit, they then realized that they were naked and they wore clothes to cover their shame. What change took place as a result of the sin? We know that man is comprised of two, contrasting features; a body and a soul. It seems that it was always understood that it was inappropriate for one's essence to be exposed, and therefore there was the necessity of some kind of 'covering', or clothing. Before the sin, Adam primarily identified himself as a soul, and his body took on the role of a kind of 'clothing' for the soul. Accordingly, there was no need for garments to act as clothing for the body, because the body was a kind of clothing in and of itself. However, after the sin, man's primary identity shifted to being that of a body. Once he viewed his body as being the ikar, he felt embarrassed when it was uncovered. Accordingly he needed clothing to cover himself.
With this insight into the relationship between body and soul, we can now gain a deeper understanding of the significance of tearing one's clothing or cutting one's body. Since the chet of Adam Harishon, man lives his life primarily focusing on himself as a body. Thus, when a person dies, one could mistakenly think that his whole being is gone forever. However, this is a serious mistake – he has only lost his body, but his soul remains extant. Accordingly, he is commanded to tear his clothing to remind him in his time of grief, that his loved one's essence has not disappeared. Only his body, which was the clothing for his soul, has been lost, however his soul is intact. This explains why it is forbidden to make a cut in one's flesh. To do so indicates a belief that this person ceases to exist in all forms.
The Torah's directives about mourning teaches not only about the correct attitude to death but also to how one should approach his life as well. With regard to death, we learn that death is not the end of a person's existence. We recognize that a person’s loved one has moved on to a higher plain of existence. Making cuts in one's body symbolizes a belief that the deceased ceases to exist in any form. Accordingly, it is a totally inappropriate action.
With regard to life, these lessons remind a person that he should not lose sight of the fact that his soul is the primary source of his identity and his body is a temporary vessel whose job is to facilitate the well-being of the soul. Accordingly, whilst one must provide for the basic physical needs of the body, he should not do so as an end in itself, rather to strengthen himself to be in a healthy physical state to embark on his spiritual endeavors. This is very difficult, given the state of man after the sin of Adam Harishon, however, the more one strengthens his recognition of the primacy of the soul, the more he will be able to put this lesson into practice.
May we all merit to understand the Torah approach to life and death.
Notes and sources
 The Shulchan Aruch is one of the most important volumes on Jewish law. It was written by Rav Yosef Karo in the 15th century.
 This is how we identify ourselves to this very day. Rav Motty Berger shlita points out that a person does not say “my body doesn't feel well”, rather he says “I don't feel well”, implying that his source of identity is his body – this demonstrates that we naturally focus on our bodies as being our essence.
From The Book “The Guiding Light 2”