OF GALILEO.

would separate without any repugnance, since the same instant of time would suffice for their separation and for the rush of the surrounding air to fill that vacuum which might remain between them. From the fact, therefore, that the lower plate follows the upper one, it is gathered that in a vacuum motion would not be instantaneous. And it is gathered together that even between the same plates there remains some vacuum at least for a very brief time; that is, for all that which passes in the movement of the ambient air while it rushes to fill the Vacuum: for if a Vacuum did not remain there, there would be no need for the rush nor for the motion of the ambient air. It will be necessary, therefore, to say that even by violence, or against nature, a vacuum is sometimes granted (although my opinion is that nothing is against nature except the impossible, which then is never). But here another difficulty is born for me: and it is that, even if experience assures me of the truth of the conclusion, the intellect does not remain entirely satisfied with the cause to which such an effect is attributed. For the effect of the separation of the two plates is prior to the vacuum that would succeed in consequence of the separation: and because it seems to me that the cause ought—if not in time, at least in nature—to precede the effect, and that of a positive effect the cause ought also to be positive, I do not remain capable of understanding how the cause of the adherence of the two plates and the repugnance to being separated—effects that are already in act—can be referred to the Vacuum, which is not, but which would have to follow. And of things that are not, none can be the operation, in accordance with the most certain pronouncement of the Philosopher.

Simp. But since you grant this Axiom to Aristotle, I do not believe that you are about to deny him another most beautiful and true one: and this is that nature does not undertake to want to do that which is repugnant to being done: from which Pronouncement it seems to me that the solution of our doubt depends: because, therefore, it is repugnant to itself to be an empty space, nature forbids doing that in consequence of which the vacuum would necessarily follow; and such is the separation of the two plates.

Sagr. Now, admitted as an adequate solution for my doubt