I don't think necessity is the mother of invention. Invention, in my opinion, arises directly from idleness, possibly also from laziness - to save oneself trouble.
When the sea goes down, there will come from the mainland boats and men. And they will find ten dead bodies and an unsolved problem on Indian Island.
A lot of additional pain and grief is caused by honesty, remarked Hercule Poirot.
How fast you go. You arrive at a conclusion much sooner than I would permit myself to do.
People are capable of surprising one frightfully. One gets an idea of them into one's head, and sometimes it's absolutely wrong. Not always - but sometimes.
Everyone's life has a tempo. Ruth's was presto whereas Miss Marple's was content to be adagio.