the cause of a stone; for some may be produced by hot, and some by cold contractions and densations, there being as many several sorts of stones as there are of other Creatures: But this is to be well noted, that as some sorts of hot contractions do make stones, so some sorts of hot dilations do dissolve them: The like of cold contractions and dilations. Again: your _Author_ speaking of the womb wherein the stone is made; _Every generated thing or being_, says he, _must of necessity have a certain place or womb where it is produced; for there must needs be places wherein things may be made before they are bred._ I answer: As there is not any body without place, nor any place without body, so the womb is not the place of the body generated, neither before nor after its generation, no more then a man can be said to be in a room when he is not there, but every body carries its place along with it. Moreover, concerning the voiding of bloody Urine, which happens sometimes in the disease of the Stone, my opinion is, That it doth not always proceed from the Stone, but many times from the breaking or voluntary opening of some Veins. But as for the cure of the disease of the Stone your _Author,_[2] is pleased to affirm, _That no disease is incurable_, and so neither the disease of the Stone, _For he himself has cured many of the Stone to which they had been obedient for some years._ Indeed, _Madam_, I fear his words are more cheerful then effectual; however it may be possible, if the Kidneys be no ways impaired, or the Bladder hurt; but if there be some such imperfection in either or both, then it is as much, in my opinion, as to say, Man can do more then Nature doth: Neither can I believe, that then any of your _Authors_ Chymical preparations, as _Aroph, Ludus, Alkahest_, and the like, if they were to be had, would do any good, no nor _Daucus_, or wild Carrot-seed, if the disease be as yet curable, will prove an effectual remedy for it, although your _Author_ is pleased to relate an example of a man, to whom it did much good; for I can affirm the contrary by other the like Examples, that it never did any good to those that used it; nor the liquor of the Birch-tree, whose venue and efficacy I do not believe to be so great as your _Author_ describes:[3] But for the stoppage of Urine, Marsh-mallow and oyl of Almonds, which he despises, I approve to be good, and better then any of his Unknown, Chymical Secrets; for those Chymical Medicines, as he himself confesses, are hard to be had, especially _Alkahest_, which is onely to be obtained by a Particular favour from Heaven, and is rather a supernatural Gift, then a natural remedy. But your _Author_ doth wisely, to commend such remedies as can never, or with great difficulty be obtained, and then to say that no disease is incurable. And so leaving him to his unknown secrets, and those to them that will use them, I am resolved to adhere to the Practice of the Schools, which I