The nineteenth article of mine in this fourteenth chapter, is this: “_All respect or variety of position of two lines, seemeth to be comprehended in four kinds_. For they are either _parallel_, or (_being if need be produced_) _make an angle_; or, (if drawn out far enough) _touch_; or, lastly, they are _asymptotes_”; in which you are first offended with the word _It seems_. But I allow you, that never err, to be more peremptory than I am. For to me it seemed (I say again seemed) that such a phrase, in case I should leave out something in the enumeration of the several kinds of position, would save me from being censured for untruth; and yet your instance of two straight lines in divers planes, does not make my enumeration insufficient. For those lines, though not parallels, nor cutting both the planes, yet being moved parallelly from one plane to another, will fall into one or other of the kinds of position by me enumerated; and consequently, are as much that position, as two straight lines in the same plane, not parallel, make the same angle, though not produced till they meet, which they would make if they were so produced: for you have nowhere proved, nor can prove, that two such lines do not make an angle. It is not the actual concurrence of the lines, but the arch of a circle, drawn upon that point for centre, in which they would meet if they were produced, and intercepted between them, that constitutes the angle. Also your objection concerning asymptotes _in general_ is absurd. You would have me add, that _their distance shall at last be less than any distance that can be assigned_; and so make the definition of the _genus_ the same with that of the _species_. But because you are not professors of logic, it is not necessary for me to follow your counsel. In like manner, if we understand one line to be moved towards another always parallelly to itself, which is, though not actually, yet potentially the same position, all the rest of your instances will come to nothing. At the two-and-twentieth article you object to me the use of the word _figure_, before I had defined it: wherein also you do absurdly; for I have nowhere before made such use of the word _figure_, as to argue anything from it; and therefore your objection is just as wise as if you had found fault with putting the word figure in the titles of the chapters placed before the book. If you had known the nature of demonstration, you had not objected this.