In early Vedic texts, we find the word guru used as an adjective meaning “heavy.” It derives from the Sanskrit root gru, whose cognate is the Greek barus and the Latin gravis. Both mean heavy as well. Thus, the word guru is connected to the English “gravity” or “gravitas,” indicating someone who is both “grave” and “heavy” with knowledge.
Most religious traditions endorse the need for such a guru or spiritual master, to one degree or another. Whether they refer to it as an abbot or a prior, a rabbi, a roshi, or what have you — the need for an experienced mentor whose knowledge far supersedes one’s own is often considered mandatory on the spiritual path. In Vaishnavism, it is a foregone conclusion: to make any real progress in pursuing
higher reality, one must have a guru.