To achieve optimal design we should start with the part that has least degrees of freedom. This is our anchor, around which we make other engineering decisions.

When you’re building a kitchen, there are a lot of things that you have to consider. Where the stove goes, if you want an island, where to put the fridge, where the windows will be. But of these the windows have the fewest degrees of freedom, if you want good light, there is going to be one wall that’s good for it and that’s where you put the windows. And there are maybe two spots on that wall where windows will look good. So you put the windows there, and then look for the next thing informed by your decision here. If there are multiple options, you can think in terms of a decision tree, but at the top of the tree you always want to start with the thing that has least degrees of freedom.

If you start with something like where to put the chairs or the table, well, that might lock you into a suboptimal decision later on, and the whole design will suffer.

(h/t Christopher Alexander)