The aura surrounding Galileo as founder of modern science disposes many of those writing about him to start in medias res with an account of his discoveries with the telescope, or with his dialogues on the world systems and the two new sciences, or with the trial and the tragic events surrounding it. Frequently implicit in such beginnings is the attitude that Galileo had no forebears and stands apart from history, this despite the fact that he was forty-six years of age when he wrote his Sidereus Nuncius and then in his late sixties and early seventies when he composed his two other masterpieces.

Attempts have recently been made by scholars to dispel this myth by giving closer scrutiny to the historical record – closer, that is, than one gets from perusing the National Edition of Galileo's works. This was a masterful collection, but begun as it was in the last decade of the nineteenth century and completed in the first decade of the twentieth, it perforce could not benefit from the historiographical techniques developed in our century. During the past twenty years, in particular, much research has been done on Galileo's manuscripts, and it sheds unexpected light on what has come to be known as Galileo's "early period" – that covering the first forty-five years of his life.