I do not know what kind of praise the Ancients thought they gave to that Painter, who not able to end his Work, finished it accidentally by throwing his pencil against his Picture; but I know very well, that it should not have obliged me, and that I should have taken it rather for a Satyre, than an Elogium.  The operations of the Spirit are too important to be left to the conduct of chance, and I had rather be accused for failing out of knowledge, than for doing well without minding it.  There is nothing which temerity doth not undertake, and which Fortune doth not bring to pass; but when a man relies on those two Guides, if he doth not erre, he may erre; and of this sort, even when the events are successefull, no glory is merited thereby.  Every Art hath its certain rules, which by infallible means lead to the ends proposed; and provided that an Architect takes his measures right, he is assured of the beauty of his Building.  Believe not for all this, Reader, that I will conclude from thence my work is compleat, because I have followed the rules which may render it so:  I know that it is of this labour, as of the Mathematical Sciences, where the operation may fail, but the Art doth never fail; nor do I make this discourse but to shew you, that if I have left some faults in my Book, they are the effects of my weakness, and not of my negligence.  Suffer me then to discover unto you all the resorts of this frame, and let you see, if not all that I have done, at leastwise all that I have endeavoured to doe.

Whereas we cannot be knowing but of that which others do teach us, and that it is for him that comes after, to follow them who precede him, I have believed, that for the laying the ground-plot of this work, we are to consult with the Grecians, who have been our first Masters, pursue the course which they have held, and labour in imitating them to arrive at the same end, which those great men propounded to themselves.  I have seen in those famous Romanzes of Antiquity, that in imitation of the Epique Poem there is a principal action whereunto all the rest, which reign over all the work, are fastned, and which makes them that they are not employed, but for the conducting of it to its perfection.  The action in Homers Iliades is the destrustion of Troy; in his Odysseas the return of Ulysses to Ithaca; in Virgil the death of Turnus, or to say better, the conquest of Italy; neerer to our times, in Tasso the taking of Jerusalem; and to pass from the Poem to the Romanze, which is my principal object, in Helidorus the marriage of Theagines and Cariclia.  It is not because the Episodes in the one, and the several Histories in the other, are not rather beauties than defects; but it is alwayes necessary, that the Addresse of him which employes them should hold them in some sort to this principal action, to the end, that by this ingenious concatenation, all the parts of them