Joseph Glanvill

It may not be impossible, but that our Faculties may be so construed, as always to deceive us in the things we judge most certain and assured.

That though we are certain of many things, yet that Certainty is no absolute Infallibility, there still remains the possibility of our being mistaken in all matters of humane Belief and Inquiry.

And for mathematical science, he that doubts their certainty hath need of a dose of hellebore.

The belief of our Reason is an Exercise of Faith, and Faith is an Act of Reason.