consisteth the original cause of the irregular motion of the Vessels, The monethly and annual alterations of the tide can depend upon nothing, save on the alteration of the additions & substractions of the diurnal period from the annual. and consequently of the Ebbing and Flowing: insomuch that if these additions and substractions should alwayes proceed in the same proportion, in respect of the Annual motion, the cause of the Ebbing and Flowing would indeed continue, but yet so as that they would perpetually return in the self same manner: But we are to finde out the cause of making the same Ebbings and Flowings in divers times greater and lesser: Therefore we must (if we will retain the identity of the cause) find the alteration in these additions and substractions, that make them more & less potent, in producing those effects which depend thereupon. But I see not how that potency and impotence can be introduced, unlesse by making the same additions and substractions, one while greater, and another while lesser; so that the acceleration and the retardment of the compound motion, may be made, sometimes in greater, and sometimes in lesser proportion.
Sagr.I feel my self very gently led, as it were, by the hand, and though I finde no rubs in the way, yet neverthelesse, like a blind man, I see not whether your Clue leadeth me, nor can I imagine where such a Journey will end.
Salv.Though there be a great difference between my slow pac't Philosophy, and your more nimble Reason, yet neverthelesse, in this particular which we are now upon, I do not much wonder, if the apprehensivenesse of your wit be a little obscured by the dark and thick mist that hides the mark, at which we aime: and that which lesseneth my admiration is, the remembrance of the many hours, many dayes, yea more, many nights that I have consumed in this contemplation, and of the many times that, despairing to bring it to a period, I have, for an incouragement of my self, indeavoured to believe, by the example of the unfortunate Orlando, that that might not possibly be true, which yet the testimony of so many credible men set before my eyes: wonder not, therefore, if this once, contrary to your custome, you do not foresee what I intend: and if you will needs admire, I believe that the event, as far as I can judge unexpected, will make you cease your wonderment.
Sagr.I thank God, that he did not permit that desperation of yours to end in the Exit that is fabled of the miserable Orlando, nor in that which haply is no lesse fabulously related of Aristotle, that so neither my self nor others should be deprived of the discovery of a thing, as abstruse as it was desirable: I beseech you, therefore, to satisfie my eager appetite as soon as you can.
Salv.I am ready to serve you: We were upon an inquiry in what manner the additions and substractions of the Terrestri-all
