_The Author in many places refers to his =Opus Saturni=, =Opus Vegetabile=, and the =Concentration of Heaven and Earth=, which Treatises, I am assured, were never printed (at least under those Titles) which also seems to be manifest from his Epistle to the =First Century=, or General Appendix, wherein he inculcates, that for want of time, he had inserted the sum of them all in that Treatise. He also mentions a Seventh part of the =Prosperity of Germany=, in the Preface to the Second Part of =Pharmacopœia Spagyrica=, which was never Printed under that Title, but I am induced to believe it is the =Novum Lumen Chymicum=, as partly appears by comparing it with the foresaid Preface. And it is evident that in some parts of his Writings he hath mentioned a Treatise by one Name, and afterwards Printed it by another, as, =The Testimonium Veritatis=, which was afterwards Printed by the Name of =Explicatio Miraculi Mundi=. As for the =Opus Saturni=, I have heard that there are some Manuscript Copies of it, and had hopes of obtaining it from two several hands, but both failed me. I have been also informed, that there are =Five Centuries= in Manuscript more than I have Printed, but could never understand in what hands they were, except one of them, =viz.= the sixth, the proprietor of which would not be so kind as to let me have it to print._ _I have (by the advice of an Honourable Person) left out the Author’s Religious and Moral Digressions, where I could do it without prejudice to the matter; as also his Apologetical Writings, except his Apology against =Farnner=, which I have printed, for as much as it is intermixt with many profitable Secrets, which perhaps, he would not have published, at least not at that time if they had not been, as it were, extorted from him by the ill Treatment of that Ungrateful Man._