Samuel Butler

It is only when you watch the dense mass of thousands of ants, crowded together around the Hill, blackening the ground, that you begin to see the whole beast, and now you observe it thinking, planning, calculating. It is an intelligence, a kind of live computer, with crawling bits for its wits.

It turns out that the very genes that turn on in cancer cells perform vital functions in normal cells. In other words, the very genes that allow our embryos to grow or our brains to grow, our bodies to grow, if you mutate them, if you distort them, then you unleash cancer.