In the publication of this work, the most acute and universally learned Mr. Edmund Halley not only assisted me with his pains in correcting the press and taking care of the schemes, but it was to his solicitations that its becoming public is owing; for when he had obtained of me my demonstrations of the figure of the celestial orbits, he continually pressed me to communicate the same to the Royal Society, who afterwards, by their kind encouragement and entreaties, engaged me to think of publishing them.  But after I had begun to consider the inequalities of the lunar motions, and had entered upon some other things relating to the laws and measures of gravity, and other forces; and the figures that would be described by bodies attracted according to given laws; and the motion of several bodies moving among themselves; the motion of bodies in resisting mediums; the forces, densities, and motions of mediums; the orbits of the comets, and such like; I put off that publication till I had made a search into those matters, and could put out the whole together.  What relates to the lunar motions (being imperfect) I have put all together in the corollaries of proposition 66, to avoid being obliged to propose and distinctly demonstrate the several things there contained in a method more prolix than the subject deserved, and interrupt the series of the several propositions.  Some things, found out after the rest, I chose to insert in places less suitable, rather than change the number of the propositions and the citations.  I heartily beg that what I have here done may be read with candor; and that the defects I have been guilty of upon this difficult subject may be not so much reprehended as kindly supplied, and investigated by new endeavors of my readers.

Cambridge, Trinity College, ISAAC NEWTON.

May 8, 1686

[Footnote A:  Sir Isaac Newton, the great English mathematician and physicist, was born at Woolsthorpe in 1642, and died at Kensington in 1727.  He held a professorship at Cambridge, represented the University in Parliament, as master of the mint reformed the English coinage, and for twenty five years was president of the Royal Society.  His theory of the law of universal gravitation, the most important of his many discoveries, is expounded in his “Philosophiae Naturalis Principia Mathematical,” usually known merely as the “Principia,” from which, this Preface is translated.]

PREFACE TO FABLES,

ANCIENT AND MODERN

BY JOHN DRYDEN. (1700)[A]

’Tis with a poet as with a man who designs to build, and is very exact, as he supposes, in casting up the cost beforehand, but, generally speaking, he is mistaken in his account, and reckons short of the expense he first intended.  He alters his mind as the work proceeds, and will have this or that convenience more, of which he had not thought when he began.  So has it happened to me; I have built a house, where I intended but a lodge; yet with better success than a certain nobleman,[1] who, beginning with a dog kennel, never liv’d to finish the palace he had contriv’d.