You've surely heard that quotation, incorrectly attributed to Albert Einstein, and trotted out incessantly, in a myriad of different contexts: "The definition of insanity is doing the same thing over and over again, and expecting a different result."
There are a lot of silly quotations floating around the world, but I think this one take the biscuit for stupidity.
First off, it's not a definition of madness. A definition describes the essence of a thing, and aims to cover all possible cases. Anyone could think of a dozen instances of madness that are not covered by this spurious definition. Someone who is a compulsive collector, like the sad case of the Collyer brothers, is clearly mad, but does not fall within the terms of this definition. Howard Hughes went bonkers in later life, but he was not doing the same thing over and over again and expecting a different result.
But it's not just its inadequacy as a definition that makes this a stupid quotation. It's not even true in itself.
Imagine someone who phones his mother forty times in a single day. There could be any amount of reasons he would do this. He might know that she is in and out of the house all day, and realize that he has a slim chance of catching her at any given time. (We'll assume she doesn't have a mobile phone. There are such people.) He might be desperately worried about her, and have no other way of contacting her-- let's say he already contacted the emergency services, and they found the house empty. Or she might be hopping mad at him and deliberately ignoring the telephone, and he's trying to wear down her resistance. He might realize this perfectly well. Maybe she even wants him to keep phoning, as a kind of expiation for whatever he did wrong.
Or imagine someone applying for jobs. He's sent out a hundred CVs (or resumés, as they are called in America) and done twenty interviews. He's attended a ton of job-searching workshops and read a whole load of "How to Get Hired" books, and he's sure he's doing everything he can. The job market is just deader than a zombie with its head blown off. So is he insane to keep trying?
Dear reader, you might be laughing that I've wasted so many words and energy refuting such a silly quotation. But why do people spend so much time and energy circulating it, when it's so obviously silly?