he 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,