I’ve been ruminating lately about when the idea of analog was born. It seems so pre-digital and of the “real world,” but it turns out is actually very much tied to the rise of computers as a way to describe their opposite. A quick NGram search shows this pretty clearly: around the late 1940s (birth of the modern digital computer era) we see both these terms explode, but basically zero uses of analog at all before this time.
We could also see analog as related to the literary term analogue, meaning an analogy. If the digital is a representation of something (discreet samples in digital audio, for example), then digital is an analogy of its physical, real-world counterpart.