It's not the towering sail, but the unseen wind that moves the ship

Set your sail to the wind.

What, sir, would you make a ship sail against the wind and currents by lighting a bonfire under her deck; I pray you excuse me. I have no time to listen to such nonsense.

Thought is the wind and knowledge the sail.

[It is] a ship with a great deal of sail but a very shallow keel.

You are not a fully fledged sailor unless you have sailed under full sail,