The outstanding merit of Deep Water is the dexterity with which it develops the psychopath's portrait from the first faint agreeable outline to the full dark horrific colours of schizophrenia. If you read crime stories at all or perhaps especially if you don't, you should read Deep Water.
I love [Highsmith] so much . . . what a revelation her writing was
My suspicion is that when the dust has settled and when the chronicle of 20th-century American literature comes to be written, history will place Highsmith at the top of the pyramid, as we should place Dostoevsky at the top of the Russian hierarchy of novelists