there might be found some one amongst mine, in which I might have been
mistaken; notwithstanding the great care I always had to admit no new
ones into my belief, of which I had not most certain demonstrations; and
not to write such as might turn to the disadvantage of any body. Which
was sufficient to oblige me to change my resolution of publishing them.
For although the reasons for which I had first of all taken it, were
very strong; yet my inclination, which alwayes made me hate the trade of
Book-making, presently found me out others enough to excuse my self from
it. And these reasons on the one and other side are such, that I am not
only somewhat concern'd to speak them; but happily the Publick also to
know them.

I never did much esteem those things which proceeded from mine own
brain; and so long as I have gathered no other fruits from the Method I
use, but onely that I have satisfied my self in some difficulties which
belong to speculative Sciences, or at least endeavoured to regulate my
Manners by the reasons it taught me, I thought my self not obliged to
write any thing of them. For, as for what concerns Manners, every one
abounds so much in his own sense, That we may finde as many Reformers as
heads, were it permitted to others, besides those whom God hath
established as Soveraigns over his people, or at least, to whom he hath
dispensed grace and zeal enough to be Prophets, to undertake the change
of any thing therein. And although my Speculations did very much please
me, I did beleeve that other men also had some, which perhaps pleas'd
them more. But as soon as I had acquired some generall notions touching
naturall Philosophy, and beginning to prove them in divers particular
difficulties, I observed how far they might lead a man, and how far
different they were from the principles which to this day are in use; I
judg'd, that I could not keep them hid without highly sinning against
the Law, which obligeth us to procure, as much as in us lies, the
general good of all men. For they made it appear to me, that it was
possible to attain to points of knowledge, which may be very profitable
for this life: and that in stead of this speculative Philosophy which is
taught in the Schools, we might finde out a practicall one, by which
knowing the force and workings of Fire, Water, Air, of the Starrs, of
the Heavens, and of all other Bodies which environ us, distinctly, as we
know the several trades of our Handicrafts, we