“

‘The interesting thing about ships is that the captains of ships have to be very careful when two ships are close together at sea, particularly in calm conditions. They tend to collide.’

‘Because of the wind blowing, and that?’ said Glenda, thinking: In theory this is a romantic-novel situation and I am about to learn about ships. Iradne Comb-Buttworthy never puts a ship in her books. They probably don’t have enough reticules.

‘No,’ said Nutt. ‘In fact, to put it simply, each ship shields the other ship from lateral waves on one side, so by small increments outside forces bring them together without their realizing it.’

” — Unseen Academicals, Terry Pratchett