Principles are ways of successfully dealing with reality to get what you want out of life.
Ray Dalio, one of the world’s most successful investors and entrepreneurs, cites principles as his key to success.
When building a "machine," design precedes people because the type of people you will need will depend on the design. As you design, create a clear mental image of the attributes required for each person to do their job well. It is futile to give responsibilities to people who do not have the qualities required to succeed. It frustrates, and inevitably angers, all parties, which is damaging to the environment.
In order to match a person to the design, start by creating a spec sheet so that there will be a consistent set of criteria that can be applied from recruiting through performance reviews. Bridgewater's spec sheets use the same bank of qualities as our Baseball Cards.
Don't design jobs to fit people; over time, this almost always turns out to be a mistake. This often happens when someone you are reluctant to let go doesn't work out, and there is an inclination to try to find out what else that person can do. Frequently managers fail to be objective about their own strengths and weaknesses, and put themselves into roles that they're not a click for.