Page:Hunterian oration, delivered in the theatre of the Royal College of Surgeons in London on February 14th 1829 (electronic resource) (IA b2148305x).pdf/14

10 and confined their labours to the perfection of their instruments?

It is true, that our intercourse with the external world brings to the understanding ideas of things, which become the subjects on which the intellectual powers are exercised. But the mind must be exercised in a series of operations, to arrive at truth. In the Pythagorean theorem it might be made obvious by inspection, that an equality subsisted between the squares of the legs and that of the hypothenuse; but it is geometry alone that can establish this proposition upon unerring certainty. The, real nature of things is unattainable by the senses.

The only real knowledge of things that we are capable of obtaining, is by directing our research into their habitudes and relations; by knowing which we arrive at the conviction, that things cannot be otherwise