Your reference to Roger Bacon is interesting. I thought of his “Epistola, “De Secretis Operibus Artis et Naturae et de Nullitate Magiae.” The contents would indeed have sounded like magic at the time, but most of what he predicts now exists. He discusses what we now call “science” can do, and here “secret” means “hidden,” perhaps just “not currently known.” He indeed says loud and clear that the “magic” of his time is worthless.

Your idea that the “secrets” of old times were often trade secrets is valid, as is the idea that accusations of secret conspiracies was – and still is – disinformation.

Modern science was in its infancy in those days, and might have been regarded as a trade secret, something to be mastered by experience and guarded like a trade secret. The question is not entirely extinct – witness disputes over what can and cannot be patented!

Dennis