As a “virus” is only a concept, early researchers had to rely on indirect observations, such as filter size as well as chemical & “pathogenic” effects assumed to be caused by invisible entities, as evidence of existence.

They relied on faith, not science – and still do today.

Source:

https://books.google.co.uk/books?id=5O0somr0w18C&printsec=frontcover#v=onepage&q&f=false

Thanks to Mike Stone of ViroLIEgy.com

If you’re a trained medical researcher please go here: Farewell to Virology (Expert Edition).

If you’re new to this topic please review this Beginners Study Guide.

The Best of Michael McKay