THE AUTHOR'S INTRODUCTION.

Judicious Reader,

There was published some years since in Rome a salutiferous Edict, that, for the obviating of the dangerous Scandals of the present Age, imposed a seasonable Silence upon the Pythagorean Opinion of the Mobility of the Earth. There want not such as unadvisedly affirm, that that Decree was not the production of a sober Scrutiny, but of an ill informed Passion; & one may hear some mutter that Consultors altogether ignorant of Astronomical Observations ought not to clipp the Wings of Speculative Wits with rash Prohibitions. My zeale cannot keep silence when I hear these inconsiderate complaints. I thought fit, as being thoroughly acquainted with that prudent Determination, to appear openly upon the Theatre of the World as a Witness of the naked Truth. I was at that time in Rome; and had not only the audiences, but applauds of the most Eminent Prelates of that Court; nor was that Decree Published without Previous Notice given me thereof. Therefore it is my resolution in the present case to give Foraign Nations to see that this point is as well under stood in Italy, and particularly in Rome, as Transalpine Diligence can imagine it to be: and collecting together all the proper Speculations that concern the Copernican Systeme, to let them know, that the notice of all preceded the Censure of the Roman Court; and that there proceed from this Climate not only Doctrines for the health of the Soul, but also ingenious Discoveries for the recreating of the Mind.

To this end I have personated the Copernican in this Discourse; proceeding upon an Hypothesis purely Mathematical; striving by all artificial wayes to represent it Superiour, not to that of the Immobility of the Earth absolutely, but according as it is mentioned by some, that retein no more, but the name of Peripateticks, and are content, without going farther, to adore Shadows, not philosophizing with requisit caution, but with the sole remembrance of four Principles, but badly under stood.

We shall treat of three principall heads. First I will endeavour to shew that all Experiments that can be made upon the Earth are insufficient means to conclude it's Mobility, but are indifferently applicable to the Earth moveable or immoveable: and I hope that on this occasion we shall discover many observable passages unknown to the Ancients. Secondly we will examine the Cœlestiall Phœnomena that make for the Copernican Hypothesis, as if it were to prove absolutely victorious; adding by the way certain new Observations, which yet serve only for the Astronomical Facility, not for Natural Neceßity. In the third place I will propose an ingenuous Fancy. I remember that I have said many years since, that the unknown Probleme of the Tide might receive some light, admitting the Earths Motion. This Position of mine passing from one to another had found charitable Fathers that adopted it for the Issue of their own wit. Now, because no stranger may ever appear that defending himself with our armes shall charge us with want of caution in so principal an Accident, I have thought good to lay down those probabilities that would render it credible, admitting that the Earth did move. I hope, that by these Consider ations the World will come to know, that if other Nations have Navigated more than we, we have not studied less than they; & that our returning to assert the Earths Stability, and to take the contrary only for a Mathematical Capriccio, proceeds not from inadvertency of what others have thought thereof, but (had we no other inducements) from those Reasons that Picty, Religion, the Knowledge of the Divine Omnipotency, and a consciousness of the incapacity of mans Vnderstanding dictate unto us.

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