At the beginning of the Torah, G-d describes His creation of Heaven and Earth and everything in them. The pinnacle of creation is man. The Torah describes giving man life by saying that G-d made man into a "nefesh chaya" (living spirit, Genesis 2:7). Targum Onkelos is the Aramaic translation of TaNaCH (Bible) and is part of the oral Torah. The Targum gives us nuances of meaning to add to our understanding of the Hebrew. It translates "nefesh chaya (living spirit)" into "ruach memalelo (speaking spirit)." By Onkelos modifying the meaning, we are taught that the ability to speak is the single most differentiating and elevating quality of the human being. Onkelos could have translated literally or chosen any other quality that sets humans apart from the rest of creation (intellect, spirituality, the ability to build, etc.).
The Jerusalem Talmud (Nedarim 9) says that the mitzva, "Love your fellow Jew as yourself" (Leviticus 19:18) is the most crucial principle in the Torah. People are born with their subjectivities and faults. In all interpersonal scenarios in general, and close relationships in particular, people approach each other with each one's shortcomings, agendas, feelings, perceptions and thoughts. Each person develops a mental reality based upon such individual factors as background, experiences, sensitivities, biases and interests. When two people approach each other, especially in a close relationship whose impact and consequences are significant, the stakes are high. When, for example, a married couple has problems, each in some way or other commonly approaches the other on the basis of his or her own inner "mental reality." If their two realities are sufficiently incompatible or dissimilar, the two collide. Their relationship can be abrasive at best, war at worst. This is typically because one or both cannot go beyond the limits of his/her own mind, so one or both is mentally locked in a box (imagine someone with a steel safe locked around his or her head)! The person sees and recognizes only what is in his or her small, dark, self-oriented box; as if there is no world out there beyond that tiny self-imposed limit. When trying to relate to someone who is outside of one's mental box, or worse - when two people come at each other locked within two different separate "mental boxes," each is force-feeding his or her reality on to the other person's unique reality. This brings collision and a conflicted relationship that has about as much constructive two-way interchange as you get from a steamroller or warring army. They are "talking AT each other, not WITH each other." Here, you have the basis for much relationship trouble.
King Solomon (Proverbs 18:21) writes, "Death and life are in the hand of a tongue, and those who love it will eat its fruit." If one speaks evil; for example slandering, fighting or embarrassing; this can bring to harming or killing people, possibly including oneself. If one speaks good things; such as Torah, peace and kindness; this is constructive and brings reward. When in a loving context in a family, this literally promotes life in this world (bringing children and a happy life for the couple) and in the eternal world (Gan Aiden). A spouse and children should be one's highest priority; for halachic, moral and practical reasons. A person's state of mind depends upon his or her closest relationship - marriage - the quality of which has profound effect on one's life. A one-sided view of a two-people relationship is "erasing" the other person. The other was not born to be erased. When you are in your own "mental box," you impose your reality on the other, negating the other's reality. Little in life is more hurting and alienating than this! Unless the couple works, each will remain in each one's own distinct reality.
Interacting with others is a practical, ongoing and central element of life. "Love your fellow Jew as yourself" is the most crucial principle of the Torah. This automatically means that pleasant, peaceful, loving, constructive, humble, thoughtful and respectful interaction is central to living Torah life. People are subjective and imperfect. There are mechanisms which G-d built into the world for genuine interchange with others; compensating for human deficiencies; training people to grow, be objective, decent and reality-based in relating to other people; and enabling people to have pleasant interaction, loving interchange, peaceful resolution of differences and healthy overlapping of different people's lives. The mechanism for all this is COMMUNICATION.
Of all the components and wonders in the universe, the most differentiating, central and elevating thing that Onkelos identifies for us is the human ability to communicate. Man is the pinnacle of creation, and his on-target communication is the pinnacle of the pinnacle! Chazal tell us that G-d created the world that there be a Jewish people who accept His Torah, that love between Jews is the Torah's most fundamental rule, that the obligation to love applies to the person one is married to and to give aggressively of oneself for the other's good in order to achieve and build love for people.
People overcome separateness and meaningfully link themselves together by communication. It is the mechanism for getting out of your self and growing beyond your own perceptions, feelings, agendas, limitations, subjectivity and selfishness. It is how you learn what a genuine and functional relationship is and requires of you, how to not mistreat the other, how to correctly treat the other and how to do so with a pleasant attitude. Communication is the means by which people learn how to recognize, be impacted by and respond to the other's needs, mental and emotional reality and what matters to the other person. This is the basis for promoting a true, satisfying and lasting relationship; relating so that the Jew succeeds in the most FUNDAMENTAL relationship (marriage), accomplishes what G-d considers to be the most FUNDAMENTAL principle in His Torah (giving-based love), achieving the most FUNDAMENTAL purpose in all of creation (the Jewish people fulfilling G-d's Torah).