I agree with the author's point. It was the founding principle of "object oriented" programming in that once the object was a black box, you could just rely on it working and let go of the implementation details. But it is also important in day to day work. I remember when I realized that I could only keep six distinct "disasters" in my head at the same time. Trying to add another one would pop one out of my head. So much of life can be simplified if you systematize things so that the thing to remember is small, like all of the stuff you take on business trips (shave kit, travel charger, noise cancelling headphones, whatever) if you put all of it in a box in your closet labelled "travel kit" then you only have to remember three things, outfits for 'n' days, your laptop, and your travel kit. Got those three and you are good to go.