The first principle is that you must not fool yourself — and you are the easiest person to fool." R. P. Feynman, - David A. Sinclair

And because aging isn't a disease by the commonly accepted definition, it doesn't fit nicely into the system we've built for funding medical research, drug development, and the reimbursement of medical costs by insurance companies. Words matter. Definitions matter.

And in his 1995 book, The Road Ahead, Bill Gates made no mention of the internet, though he substantially revised it about a year later, humbly admitting that he had “vastly underestimated how important and how quickly” the internet would come to prominence.2

They have also evolved to require a molecule called nicotinamide adenine dinucleotide, or NAD. As we will see later, the loss of NAD as we age, and the resulting decline in sirtuin activity, is thought to be a primary reason our bodies develop diseases when we are old but not when we are young.