Pick up a ream of copy paper in the United States and read the wrapper. It says 8.5 × 11 in, and it says 20 lb. Neither number describes the paper inside. An A4 ream has no such problem. It says 210 × 297 mm and 80 g/m². Both of those are properties of the sheet you are holding: its dimensions, and its mass divided by its area. Check them with a ruler and a kitchen scale and they come out right. ...
The fountain pen is a small object with a large argument inside it. Every serious pen is a thesis about what writing is for, and no two pens argue the point more cleanly than the Lamy 2000 and the Waterman Carène. Both are modern classics, both have been in production for decades, and both cost roughly the same money. They could not be less alike. One is a German machine that hides its nib; the other is a French yacht that displays it. Choosing between them is not choosing between two pens. It is choosing between two theories of the examined life. ...