agreeable to the Cavities it lodged it self in. Such Adherents as these are, I am more inclined to believe, are the Cause of the unsuccessful Attempts on _Cancers_, than any _Acid_ in the Blood; for I am of opinion there are few Persons unacquainted with Medicines that are capable of correcting its _Acidity_ when it happens; and had the Cure of _Cancers_ depended on that, I am positive they would not at this Time have had such ill Character. We have before shewed that _Cancers_ have generally their Rise from a Blow or Bruise, and that when the Body is in an healthful Condition, and the Blood and _Lympha_ temperate and sweet: Now if there always is an _Acidity_ of the Blood when Persons are afflicted with _Cancers_, the _Cancers_ must sometimes cause it, and not the _Acid_ in the Blood the _Cancers_, as is the Opinion of most of the Moderns. What has been hitherto said, is sufficient to prove that if Men will be always so sluggish as to acquiesce in the Dictates and Dogmatical Positions of their Predecessors, and not exert their Faculties in endeavouring to undeceive themselves; we must no longer expect our Art will receive any Advancements, but as Slaves to their Opinions content our selves with what we know already. Were not _Parisani_, _Riolan_ the Son, and _Plempius_, so much in the Interest of the Ancients, that when our Country-man, the assiduous _Harvey_, had discovered the Circulation of the Blood, they not only opposed his plain Demonstrations, but engaged in vigorous Disputes against him, tho’ at the last they were obliged shamefully to recant their Follies. _Celsus_ tells us, _Vix ulla perpetua Præcepta Ars Medicinalis recipit_; scarce any of the Precepts of the Medicinal Art are perpetual. And shall we engage then in the List with a few opinionative Men, that ground their Course of Practice on those Methods only, in which they have been brought up, and implicitly assent to the Conjectures of others. No certainly, this would be to strangle Truth, and extinguish the Vigour of our Wits with precarious Authorities. Consonant to this, Dr _Paxton_, in his lately published Treatise, tells us, _Thus Men, out of a trifling Distrust of their own Parts, will not use them; or out of Laziness of Temper, will not employ them, chusing rather to be wise or learned, by being adorned with Others Whimsies, than undergo any Labour, Fatigue, or Trouble of being really so_. I believe there are some Men that would rather contradict their Senses than deny the Authority of a darling Opinion: Of this, we have a sufficient Proof in an Instance, related by an _Italian_ Author before-mentioned. He tells us, _That a certain Publick Reader long Time versed and grown Old in the Books of_ Aristotle _being one Day present at a Dissection, and clearly seeing that the_ Vena Cava _takes its Rise from the Liver, confessed with Astonishment what his Senses discovered to him, but that he ought not therefore, by crediting his