Moats around castles and fortresses served to deter easy direct attack. A lot of people don’t know that they also served to collapse any potential underground tunneling. Bruce Lee often preached for people to be like water: fluid, yet immensely and and inexorably powerful. Water is the most patient and universal substance on Earth. Another thing most people don’t know is that the tide doesn’t actually go in and out. It is actually the Earth rotating into the bulge of water created by the moon’s gravitational force. During a full moon, the higher tide is created by the sun’s gravitational force following along the line opposite the Moon.
I don’t have a metaphor or a life lesson to tie this up neatly.