every Age, Nation, or Creature, has always the like diseases; for as all the actions of Nature vary, so also do diseases. But to speak of the Plague, although I am of opinion, that the Plague of Beasts doth not infect Men, unless they be eaten; nor the plague of Men, Beasts; yet Magistrates do wisely in some places, that in the beginning of the plague of Men, they command Dogs and Cats to be kill'd, by reason, as your _Author_ saith, _The skins and flesh of Brutes may be defiled with our Plague, and they may be pestiferous contagions unto us._ I will add one thing more, which doth concern the Poyson of Measels, whereof your _Author_ is saying,[2] That _it is onely proper to humane kind._ What kind of Measles he means, I know not; but certainly Hogs are often affected with that disease, as is vulgarly known; but whether they be different diseases in their kinds, and proceed from different motions, I will let others inquire. And so I rest, Madam, _Your faithful Friend_ _and Servant._ [1] In the Plague-grave, _ch._ 17. [2] _Ch._ Call'd, _The Lunar Tribute_. XL. _MADAM,_ Concerning the disease of the Stone, your _Author_ seems to be of an opinion, That the stone in the Bladder, and the stone in the Kidnies, are not made after one and the same manner: For, says he,[1] _The Bladder and the same Urine in number procreates a duelech of another condition, then that which is made in the Kidney._ And truly, _Madam_, it may be so; for there are several ways or modes in irregularities, as well as regularities, and not every kind is alike, no not every Particular, but there is some difference between them: Wherefore, it may very well be, that the corporeal motions that make the stone in the Kidneys, are not just alike to those that make the stone in the Bladder; and as each sort of stone is different, so their particular causes ought to be different; but this is to be observed, that generally all diseases which produce hardness, are made by contracting, condensing and retenting motions, and therefore the remedies of them must be dilating, rarifying and dissolving. Next your _Author_ says, _The Stone is not bred by heat, but heat is rather an effect of the stone; neither is a certain muscilage, or a slimy, snivelly Phlegme the cause or matter of the stone, but the stone is the cause of the phlegme._ But, in my judgment, it seems more probable, that a slimy matter is more proper for a stone to be made of, then that a stone should make slime, except it be in its dissolution; that is, when the stone, as in its generation or production it did change from a slimy or liquid substance to a stone by condensing and contracting motions, doth, by dilating and rarifying motions, dissolve again into such a liquid and slimy body. I will not say always, to wit, that the stone must needs be resolved into a slimy matter, but oftentimes it may be so. Neither can I absolutely affirm that either heat or cold onely is