Chapter LVI: Section II: The Discipline of Pure Reason in Its Polemical Employment

This section contains an admirable defence of the value of scepticism.

“Even poisons have their use. They serve to counteract other
poisons generated in our system, and must have a place in every
complete pharmacopeia. The objections against the persuasions and
complacency of our purely speculative Reason arise from the very
nature of Reason itself, and must therefore have their own good use
and purpose, which ought not to be disdained. Why has Providence
placed many things which are closely bound up with our highest
interests so far beyond our reach, that we are only permitted to
apprehend them in a manner lacking in clearness and subject to
doubt, in such fashion that our enquiring gaze is more excited than
satisfied? It is at least doubtful whether it serves any useful
purpose, and whether it is not, indeed, perhaps even harmful to
venture upon bold interpretations of such uncertain appearances.
But there can be no manner of doubt that it is always best to grant
Reason complete liberty, both of enquiry and of criticism, so that
it may be without hindrance in attending to its own proper
interests. These interests are no less furthered by the limitation
than by the extension of its speculations; and they will always
suffer when outside influences intervene to divert it from its
natural path, and to constrain it by what is irrelevant to its own
proper ends.”[1705] “Whenever I hear that a writer of real ability
has demonstrated away the freedom of the human will, the hope of a
future life, and the existence of God, I am eager to read the book,
for I expect him by his talents to increase my insight into these
matters.”[1706]