“I sometimes think that the only real purpose of an initial design is to evolve some sort of of plan to get one started in an otherwise confusing and complex situation.”
Bill Mollison

Permaculture: A Designer's Manual

Generative vs. Descriptive

“Does the DNA contain a full description of the organism to which it will give rise? The answer is no. The genome contains instead a program of instructions for making the organism – a generative program …

A descriptive program, like a blueprint or a plan, describes an object in some detail, whereas a generative program describes how to make an object … consider Origami … by folding a piece of paper in various directions, it is quite easy to make a paper hat or a bird from a single sheet. To describe in any detail the final form of the paper with the complex relationships between its parts is really very difficult, and not of much help in explaining how to achieve it. Much more useful and easier to formulate are instructions on how to fold the paper … a generative program for making a particular structure.”

Lewis Wolpert – Principles of Development
quoted in
Christopher Alexander – The Nature of Order – Book 2: The Process of Creating Life

Nature of Order - Table of Contents"