I don't think necessity is ...

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.
 Agatha Christie

Quotes from the same author

Good advice is always certain to be ignored, but that's no reason not to give it.
 Agatha Christie
I'm sorry, but I do hate this differentiation between the sexes. The modern girl has a thoroughly businesslike attitude to life! That sort of thing. It's not a bit true! Some girls are businesslike and some aren't. Some men are sentimental and muddle-headed, others are clear-headed and logical. There are just different types of brains.
 Agatha Christie
Any woman can fool a man if she wants to and if he's in love with her.
 Agatha Christie
A mother's love for her child is like nothing else in the world. It knows no law, no pity, it dares all things and crushes down remorselessly all that stands in its path.
 Agatha Christie
Then there are some minor points that strike me as suggestive - for instance, the position of Mrs. Hubbard's sponge bag, the name of Mrs. Armstrong's mother, the detective methods of Mr. Hardman, the suggestion of Mr. MacQueen that Ratchett himself destroyed the charred note we found, Princess Dragomiroff's Christian name, and a grease spot on a Hungarian passport.
 Agatha Christie