Part of this is that analog vs digital isn’t the right term. Vacuum tubes are completely irrelevant to the point he is trying to make, and confuse the reader.

The point he’s trying to make (which unfortunately I’m unable to explain right now better than he can) is about the emergent properties of systems made up of independnt entities in a rigid form and how this is a type of computing that differs from what we usually think of as computing. The example he have about DNA vs the brain sort of gives an example of this. DNA is coded similarly to computers, and in many ways cells are like computers/programs (that happen to self-propagate according to their software). On the other hand, brains are this other type of “system” computer made up of a combination of independent actors (neuron cells), a regidid but adaptable structure (the physical structure of the brain), inputs, and information sent between the individual actors. This is very similar to a million computer-regulated human systems where we react to information we receive through the platform, and we relay our reaction to the system, and that reaction affects how the system interacts with other individual actors.