Study with a chavruta, or partner, is a hallmark of traditional Jewish learning. Together you break your heads on the texts. Two minds applied to a problem are almost always better than one.
Each checks and corrects the misconceptions of the other, questioning and sharpening the other's ideas, while the necessity of articulating one's thoughts to another person brings greater clarity than learning alone. Indeed, the Talmud goes so far as to say that one who learns Torah alone becomes stupid! (Berachot 63a)
Chavruta comes from the Hebrew word meaning, simply, "friend." Pirkei Avot (Ethics of the Fathers) states the fundamental importance of companionship in Jewish learning (and in general): "Make for yourself a teacher, find yourself a friend, and judge every person favourably."
Commentators explain the final, apparently unrelated, clause as being an essential requirement for achieving the first two. Being endlessly judgmental and critical makes it very hard to commit to, and keep, either friends or teachers.
There are numerous statements in the sources that stress the essential sociability of study. The unbearability of life without scholarly companionship is poignantly expressed about Honi the Circle-maker, "Either chavruta or mituta," "either friendship or death" (Taanit 23a).
Some suggest that the quality of relationship between the chavrutas is as important religiously as the content of what is studied. "When two scholars of Torah listen to one another, God hears their voices," says the Talmud (Shabbat 63a).