" These autonomous, self-regulating properties of holons within the growing embryo are a vital safeguard; they ensure that whatever accidental hazards arise during development, the end-product will be according to norm. In view of the millions and millions of cells which divide, differentiate, and move about in the constantly changing environment of fluids and neighbouring tissues-Waddington called it 'the epigenetic landscape'-it must be assumed that no two embryos, not even identical twins, are formed in exactly the same way. The self-regulating mechanisms which correct deviations from the norm and guarantee, so to speak, the end-result, have been compared to the homeostatic feedback devices in the adult organism-so biologists speak of 'developmental homeostasis'. The future individual is potentially predetermined in the chromosomes of the fertilised egg; but to translate this blueprint into the finished product, billions of specialized cells have to be fabricated and moulded into an integrated structure. The mind boggles at the idea that the genes of that one fertilised egg should contain built-in provisions for each and every particular contingency which every single one of its fifty-six generations of daughter cells might encounter in the process. However, the problem becomes a little less baffling if we replace the concept of the 'genetic blueprint', which implies a plan to be rigidly copied, by the concept of a genetic canon of rules which are fixed, but leave room for alternative choices, i.e., flexible strategies guided by feedbacks and pointers from the environment. But how can this formula be applied to the development of the embryo? "
― Arthur Koestler , The Ghost in the Machine