This illustration depicts the protagonist, having been newly transformed into a water baby, learning from a salmon and his wife of the existence of other water babies.
A weird fake science presentation from real scientists and professional people.
Madness string 4256
Most of his disciples were common laborers and likely would have had little to no formal education. So who exactly would have taught them to read and write? I think people can't grasp the fact that throughout history most people were illiterate, and that simply because much of the world has decent literacy rates that the same situation existed in the past.