In his Magicum he gives his reasons for breaking with tradition.

"I did," he says, "embrace at the beginning these doctrines, as my adversaries (followers of Galen) have done, but since I saw that from their procedures nothing resulted but death, murder, stranglings, anchylosed limbs, paralysis, and so forth, that they held most diseases incurable....

therefore have I quitted this wretched art, and sought for truth in any other direction.

I asked myself if there were no such thing as a teacher in medicine, where could I learn this art best?
Nowhere better than the open book of nature, written with God's own finger." We shall see, however, that this "book of nature" taught Paracelsus some very strange lessons.

Modesty was not one of these.