Quote:and the good change survives to enter into another state of mutation
Poor phrasing there. There is no 'good' or 'bad,' in the process. Either a change is beneficial for the particular environment the organism finds itself in or it is not.
When our distant ancestors were climbing around in trees a mutation which allowed bi-pedalism would have done them little good. But once the trees die out do to climate change and they find themselves on a grassland such a change to bi-pedalism becomes useful in terms of increasing their field of vision. Same change. Useful in one instance and not useful in the other.
Oversimplified but there are creatards here so things have to be kept simple.