Glyphs having identical meanings (关, 關) apparently with equivalent internal elements may tell the story best.「Emissions」with the original form of「heaven」(middle stroke is wider than the top stroke) within a「gateway, methodology.」Older version uses「multiple loose and dripping stench emissions」(幺, same as in the glyph for 'medicine' 樂) with「divine, hair-raising experiences」within the「gateway」as something TO BE CONCERNED ABOUT. Indicates a CONNECTION, being INVOLVED since if a person became ill in this manner, then everyone know there was only one way it occurred, and NO TURNING BACK, NO GOING BACK to the way it was before. Both older glyphs lead to the conclusion that the glyph represents「heaven's gate.」Traditional fonts display 关 as「arrow, sick penis」(矢) with「and the other side, too」at the top-right, suggesting that if one is struck on both sides by an arrow, or multiple infections and illness, the predictable result will be certain death and a one-way pass into heaven, checking in but unable to check out as it were, BARRIER, CLOSED OFF, SHUT, NO ACCESS PAST THIS POINT.
　Suggests barring participation in the communal sex activities, the bonobo-style orgies due to illness, or being underaged (was that possible?). Original element of「methods of many loose and dripping emissions with prepubescent female」indicate pedophilia and NO TURNING BACK, NO GOING BACK to the way we were. Etymology in English of「pedo, paedo」from Latin and/or Greek refer to one or all of「young and small child」「feet」「feces and flatulence, anal emissions.」…just coincidences? perhaps.
　A MOUNTAIN PASS functions as an unavoidable BARRIER, ONE WAY THROUGH or THE ONLY WAY to pass, and a CONNECTION from one side to the other.
　Scholars explain these elements as treadles that are actuated by thrusting downward with one's feet on one side of a loom and then the other side, too, but note the elements for fibers are not yet spun into threads, and cocoon fibers cannot directly be used to make textiles with a loom. Nevertheless, a treadle is a wooden beam that is tread upon with a person's foot in order to raise heddles, which in turn raised a set of warp threads within the loom. Treadles being intricately connected (built into the construction of the loom) and to the many warp threads, albeit not directly but via the heddles. Reasoning continues that this same large beam could be used to bar a gate.

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: mountain pass; to close; to shut; to turn off; to concern; to involve
Unihan extended: frontier pass; close; relation
EDRDG: connection; barrier; gateway; involve; concerning