Newton

In the novel Evil Under the Sun, Newton is mentioned by Poirot. Poirot mentions that someone had written a learned treatise on the difference solitary confinement would mean to Beau Brummel or to Newton. He brought this up because he was making the point that Arlena Marshall "would practically not exist in solitude", and so even though she had said that she wanted to be alone on the morning of her death, she must have been going to meet someone.