All which presents itself now to my mind, urging, persuading, and even compelling me to demonstrate in your case the purpose for which Heaven sent me into the world and caused me to make profession of the order of chivalry to which I belong, and the vow I took therein to give aid to those in need and under the oppression of the strong.
And this demonstration is just the thing for me for that other book I am writing, the ’Supplement to Polydore Vergil on the Invention of Antiquities;’ for I believe he never thought of inserting that of cards in his book, as I mean to do in mine, and it will be a matter of great importance, particularly when I can cite so grave and veracious an authority as Senor Durandarte.
…or by reasons which depend upon the examination of the understanding or are founded upon the articles of faith, but must have examples that are palpable, easy, intelligible, capable of proof, not admitting of doubt, with mathematical demonstrations that cannot be denied, like, ’If equals be taken from equals, the remainders are equal:’ and if they do not understand this in words, and indeed they do not, it has to be shown to them with the hands, and put before their eyes, and…
As she uttered these words, with incredible energy and swiftness she flew upon Lothario with the naked dagger, so manifestly bent on burying it in his breast that he was almost uncertain whether these demonstrations were real or feigned, for he was obliged to have recourse to all his skill and strength to prevent her from striking him; and with such reality did she act this strange farce and mystification that, to give it a colour of truth, she determined to stain it with her own…
The duke came to himself slowly and like one recovering consciousness after a heavy sleep, and the duchess and all who had fallen prostrate about the garden did the same, with such demonstrations of wonder and amazement that they would have almost persuaded one that what they pretended so adroitly in jest had happened to them in reality.
There are no more uses of "demonstrate" in the book.