drop, pure
涓 centers on a tiny amount of liquid: a single drop, or the purity that comes from being a small, clean droplet.
涓 combines 氵 (water) with 肙, which likely contributes the sound and may relate to a small worm or insect, suggesting a tiny drop of water.
Water 氵 beside 肙, a shape that looks like a tiny creature with a small body and a mouth. Imagine a single pure drop of water falling from the mouth of a tiny worm.
For ケン, picture a single drop of water falling onto a can: can -> ケン, and the drop makes a pure, clean sound.
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slow but steady wins the race; constant effort will result in success; constant dripping wears away a stone