The drops of rain make a hole in the stone, not by violence, but by oft falling.

[Gutta cavat lapidem, non vi, sed saepe cadendo.]

Other Authors and Sources
Latin proverb

Alt. trans.:

• "The rain dints the hard stone, not by violence, but by oft-falling drops."
• "The drop of rain maketh a hole in the stone, not by violence, but by oft falling."
• "The drop hollows out the stone not by strength, but by constant falling."
• "The drop hollows the stone, not with force but by falling often."
• "Dripping water hollows out the stone not by force, but by continually falling."

Some famous usages include Lucretius, De rerum natura, Book 6, l. 312: "The ring on the finger is tapered by being worn, the dripping water hollows out the stone, the plow is subtly worn by the impact of the fields." [anulus in digito subter tenuatur habendo, stilicidi casus lapidem cavat, uncus aratri, ferreus occulte decrescit vomer in arvis]

Similarly Ovid, Ex Ponte, 4.10.5: "The drop hollows out the stone, the ring is worn by use, and the curved ploughshare is rubbed away by the pressure of the earth." [Gutta cavat lapidem, consumitur annulus usu, et teritur pressa vomer aduncus humo.]

Made famous in English by Hugh Latimer, "Seventh Sermon before Edward VI" (1549). Similarly, John Lyly, Euphues (1580): "The soft droppes of rain perce the hard marble; many strokes overthrow the tallest oaks."