1. Philosophical Investigations (1945)
The preface is astounding and beautiful. It is so emotionally raw, honest, unpretentious. It is completely human. It embarasses anyone who would pretend to be otherwise.
50. There is one thing of which one can say neither that it is one meter long nor that it is not one meter long, and that is the standard meter in Paris. But this is, of course, not to ascribe any extraordinary property to it, but only to mark its peculiar role in the language game of measuring with a meter rule.” (Sect. 50) This is important to my work as I believe the same can be said of light itself, which can also function as a ruler. Because it is a ruler, it cannot itself be ruled (e.g. measured). The term ruler her is quite appropriate. Light is the ruler of spacetime, physically and metaphysically.