We can explain a simple process step by step but a complex system is better addressed part by part. Object-oriented programming introduced this shift into programming allowing for the creation of much more capable systems by those who had made the transition.
Alexander sought out the patterns that made a town work. A town is of course a system that works well or doesn't. We modeled object-oriented programming guidance as patterns following the examples Alexander used for towns. The more we learned of his work, the more we understood the challenges before us.