This blog post elaborates on how unit conversion can be seen as a sense of polymorphism to arbitrary "perceivers", where natural parametric polymorphism considers the function to be 1st person. It concludes with the idea that perceptive, discrete beings (identities) are indeed the 1st person function, and all measureable units with just, provably equalitable conversions between them satisfy the definition of ad-hoc polymorphism through unit conversion.