ut, paradoxical as it may seem, this
will ever be the case in the progress of natural science, so long as the
works of God are, like himself, infinite and inexhaustible. In
completing one discovery we never fail to get an imperfect knowledge of
others, of which we could have no idea before; so that we cannot solve
one doubt without creating several new ones.

Travelling on this ground resembles Pope's description of travelling
among the Alps, with this difference, that here there is not only
_succession_, but an _increase_ of new objects and new difficulties.

So pleas'd at first the tow'ring Alps we try,
Mount o'er the vales, and seem to tread the sky.
Th' eternal snows appear already past,
And the first clouds and mountains seem the last,
But those attain'd, we tremble to survey
The growing labours of the lengthen'd way.
Th' increasing prospect tires our wand'ring eyes,
Hills peep o'er hills, and Alps on Alps arise.

ESSAY ON CRITICISM.

Newton, as he had very little knowledge of _air_, so he had few doubts
concerning it. Had Dr. Hales, after his various and valuable
investigations, given a list of all his _desiderata_, I am confident
that he would not have thought of one in ten that had occurred to me at
the time of my last publication; and my doubts, queries, and hints for
new experiments are very considerably increased, after a series of
investigations, which have thrown great light upon many things of which
I was not able to give any explanation before.

I would observe farther, that a person who means to serve the cause of
science effectually, must hazard his own reputation so far as to risk
even _mistakes_ in things of less moment. Among a multiplicity of new
objects, and new relations, some will necessarily pass without
sufficient attention; but if a man be not mistaken in the principal
objects of his pursuits, he has no occasion to distress himself about
lesser things.

In the progress of his inquiries he will generally be able to rectify
his own mistakes; or if little and envious souls should take a malignant
pleasure in detecting them for him, and endeavouring to expose him, he
is not worthy of the name of a philosopher, if he has not strength of
mind sufficient to enable him not to be disturbed at it. He who does not
foolishly affect to be above the failings of humanity, will not be
mortified when it is proved that he is but a man.