Propulsion.

A ship can have a wonderful navigator, a superb captain and a glorious destination. But if it doesn't have some method of propulsion, it just won't move.

My ship has a sail. It extends, and catches the wind, when it is there, and salt mists that allows it to glide quietly forward.
It also has a huge outboard motor, that, when started, speeds my vessel forward in blinding sprays of disturbed water in its wake.
In addition to this, it also has a furnace that burns things to make a propellor spin, and a great smog spouts from its chimney as it ploughs forward into the face of the wind.
And finally, it has its sweeps. Long oars that are hard to move, they splinter hands, they flop and crunch on the water. And inch by inch. The ship. Moves. Along.


This is a metaphor. I'm not talking about boats at all really. Can you tell? I bet you can.