Although I should go through the calculations, I choose not to. Partly because the deed is done, and partly because of the general relationship between number of equations I produce on the processes around the house their inverse relationship to the general state of harmony.

At any rate, I will say that I should run the numbers.

My wife recently returned from a 435-mile trip from her parents with a number of rocks in the car. Yes, rocks. These are not a few geologic samples. These are for landscaping. A large number of them. She thought they were pretty. I thought, well, if we look around here, we could buy rocks within 10 miles of our home and even though we would have to pay for them, the cost may well be far below the cost of the “free” rocks she brought home. Two words need applied: transport costs.

If we take the weight of the rocks, the decrease in fuel efficiency due to the extra weight of the rocks in the car, the cost of extra gas to account for the increase in weight of the vehicle with the rocks in it. then we start to approach the true cost of the rocks.

For bringing back rocks to be worth it:

Cost of transport of “free” rocks < cost of local “non-free” rocks

There is a transport cost even for the local rocks, but we will assume this is negligible, being so close, meaning far less that the 435 miles of transport of the rocks from out of state.

Again, the numbers were not run, if only for the sake of peace and tranquility in the home.