Pliny the Elder

The Natural History is thirty seven books, and Pliny says in the preface that it holds twenty thousand facts worth knowing, drawn from two thousand volumes by a hundred authors. He supplied an index book listing his sources for each of the others, which makes the work a bibliography of a library that has otherwise perished, and much of what is known about lost Greek and Roman writing on medicine, minerals and botany is known because he cited it.

The theology in it is Stoic and stated openly in the second book: the world itself is what should be understood as divine, eternal, boundless and without beginning, and the crowd of gods with human passions and marriages is a symptom of human weakness. That does not stop him recording every rite and remedy he can find. His book on the origins of magic is hostile, deriving the art from Persia and treating it as fraud, and is also the fullest surviving Roman account of what magi were believed to do. His description of druids cutting mistletoe from an oak with a golden sickle, catching it in a white cloak and sacrificing two white bulls, is a few sentences long and is the foundation of nearly everything later Europe thought it knew about them.

The transmission is the interesting part. Solinus excerpted him in the third century, Isidore of Seville worked from him, medieval encyclopaedias and lapidaries and herbals mined him steadily, and by the time Renaissance magical texts were being compiled a great deal of their content had reached them through that chain at two or three removes. The virtues attributed to particular stones, the amulets, the plant remedies gathered at particular hours, the whole principle that things which resemble one another act on one another: much of that reaches the grimoires as Pliny material, stripped of the scepticism he attached to it.

That is the irony worth recording. He set out to document credulity and produced the reference work that sustained it, because a hostile description is still a description and copyists keep the recipe and drop the objection. The atlas cites him constantly for that reason and cites him with care, since he is reporting what was believed rather than what was true. He died in the eruption of Vesuvius in 79, having taken ships toward the shore both to observe the phenomenon and to take people off, and the account of it comes from his nephew, who was watching from across the bay.