the patience of water, proving that slow and steady carves the deepest canyons
means To flow slowly in a thin stream or in small drops, or to arrive or happen gradually and in small amounts.
from Likely a Middle English word, 'triklen,' that imitates the sound it describes — the soft, repetitive patter of small drops. Such echoic words don't descend from grand roots so much as they're born straight from the ear, the language reaching for a noise and keeping it. Its exact ancestry is uncertain, as is often the case with words that began as mimicry rather than meaning.
trickle down economics — reagan's 1981 tax cut policy based on the theory that cuts to top earners benefit the poor
trickle charging — slow continuous charging method used to maintain battery levels in cars and devices without overheating