Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/189

 son of its great resistance to the division made by the hull of the ship, doth with great noise resist the same; nor doth it permit it of a great while to acquire that velocity which the wind would confer upon it, were the obstacle of the water removed. Perhaps Simplicius you have never considered with what fury the water besets a bark, whil'st it forceth its way through a standing water by help of Oars or Sails: for if you had ever minded that effect, you would not now have produced such an absurdity. And I am thinking that you have hitherto been one of those who to find out how such things succeed, and to come to the knowledg of natural effects, do not betake themselves to a Ship, a Crosse-bow, or a piece of Ordinance, but retire into their studies, and turn over Indexes and Tables to see whether Aristotle hath spoken any thing thereof, and being assured of the true sense of the Text, neither desire nor care for knowing any more.

This is a great felicity, and they are to be much envied for it. For if knowledg be desired by all, and if to be wise, be to think ones self so, they enjoy a very great happinesse, for that they may perswade themselves that they know and understand all things, in scorn of those who knowing, that they understand not what these think they understand, and consequently seeking that they know not the very least particle of what is knowable, kill themselves with waking and studying, and consume their days in experiments and observations. But pray you let us return to our birds; touching which you have said, that the Air being moved with great velocity, might restore unto them that part of the diurnal motion which amongst the windings of their flight they might have lost; to which I reply, that the agitated Air seemeth unable to confer on a solid and grave body, so great a velocity as its own: And because that of the Air is as great as that of the Earth, I cannot think that the Air is able to make good the losse of the birds retardation in flight.

Your discourse hath in it much of probability, and to stick at trivial doubts is not for an acute wit; yet neverthelesse the probability being removed, I believed that it hath not a jot more force than the others already considered and resolved.

It is most certain that if it be not necessarily concludent, its efficacy must needs be just nothing at all, for it is onely when the conclusion is necessary that the opponent hath nothing to alledg on the contrary.

Your making a greater scruple of this than of the other instances dependeth, if I mistake not, upon the birds being animated, and thereby enabled to use their strength at pleasure against the primary motion in-bred in terrene bodies: like as for