Parashat Yitro:

In Exodus 20 and Deuteronomy 5 the Ten Commandments appear in their most recognizable form. Among their differences, Deuteronomy prohibits both coveting and craving whereas Exodus forbids only coveting. Both appear to prohibit a mental state.
Some commentaries distinguish coveting as an organizing principle for the Ten Commandments. The legal midrash on Exodus, Mekhilta (3rd century c.e.) explains that if a person craves something, ultimately that person will covet. If s/he covets, ultimately s/he will steal.  Each level leads to the next, until all of the Ten Commandments may be broken. Here the connection between action and thought becomes apparent. Simply prohibiting activities does not prevent sinning because we are motivated by our thoughts and emotions. Better to refrain from those intangible, mental catalysts that lead us astray.
Similarly, Rabbi J. H. Hertz in his 20th century commentary claims that the Tenth Commandment prohibits "anything that we cannot get in an honest and legal manner."  He asserts that the law "goes to the root of all evil actions -- the unholy instincts of predatory desire, which are the spring of nearly every sin against a neighbor." (The Pentateuch and Haftorahs, p. 300)
The medieval biblical commentators Ibn Ezra and Sforno view the prohibition of coveting as forbidding the desire for specific objects. Ibn Ezra begins by saying that we must wonder how the Torah can forbid the desire for something delightful to the eye.  After all, the delights of the senses are gifts of God! But a student must train himself to suppress longing for objects God has not planned for him to possess.  Thus, avoiding coveting is a matter of training beginning in early childhood, a lesson parents do well to inculcate. Similarly, Sforno tells us that we should simply view everything that belongs to someone else as beyond our reach. The problem is not that we desire things in general, but that we desire specific objects or persons that God has prohibited.
Alternatively, the nineteenth century commentary known as Malbim distinguishes between coveting and craving, not as degrees of emotional intensity, as does the midrash Mekhilta, but as a result of an internal or external driver:  either imagination or sight. We do not covet our neighbor's spouses as a result of imagination. It is only seeing another person in the flesh that we covet that person. But we can covet our neighbor's wealth by imagining what it would be like to possess it ourselves, without actually experiencing anything. Both are common sins in the affluent society.
This week with the scandals of television anchor Brian Williams and UMKC Bloch Business School, we witness individuals who desired what they could not have and did not earn. Neither really needed the status brought by their exaggerations, but they needed to appease some inner desire to prove a different status. They risked so much just to appease their craving! In retrospect, recognizing and restraining the desire would have made them happier with life. We, too, should remember that coveting surrounds us all of the time. We do well to guard our emotions and desires from betraying our souls.
The Torah generally demands avoidance of particular actions rather than thoughts. But in this prohibition of coveting we recognize a fundamental emotion or thinking pattern that plays a major role in our transgressions against God and our neighbors. For that reason it assumes a place in the most important law code in the Torah.
Shabbat shalom.