Some believe it is only great power that can hold evil in check, but that is not what I have found. It is the small everyday deeds of ordinary folk that keep the darkness at bay. Small acts of kindness and love.

See: J.R.R. Tolkien for more quotes by Tolkien

While not technically a quote by Tolkien, it is a quote from an adaption of one of his works that very much fits within the world and narrative he wrote, and thus warrants inclusion among his works.