Charubel's image for this degree is precise machinery: a large undershot water-wheel. The adjective is the interpretive key. An overshot wheel is fed from above, water delivered to it by an aqueduct so that gravity does the work; an undershot wheel stands in the stream itself and is turned from below, by whatever current the river actually supplies. It is the humbler, older, less efficient design, and it works anywhere the water flows.
Read against the twenty third degree of Leo the image argues with the sign's preference for being supplied from above, by right, by inheritance, by acclaim, and proposes instead a power taken directly from the passing current, strength that engages the world at its own level and converts flow into work. The wheel does not command the river; it consents to stand in it. There is patience in the picture, and modesty, and a certain weather-worn reliability, the mill that grinds every day the stream runs. The shadow is dependency of a different kind, a wheel that turns only as fast as its river and stops in drought, output hostage to conditions it cannot raise.
On a natal Sun, Mars or Midheaven this degree tends to mark careers and vitalities driven by immersion, people who draw force from the traffic of ordinary life rather than from elevated positions, and its counsel is double: keep the wheel in the water, and know the river's seasons, since what turns you also meters you.