Full Idea
The structure of your reasoning must be rickety and defective, if the senses on which it rests are themselves deceptive.
Gist of Idea
If the senses are deceptive, reason, which rests on them, is even worse
Source
Lucretius (On the Nature of the Universe [c.60 BCE], IV.518)
Book Reference
Lucretius: 'On the Nature of the Universe', ed/tr. Latham,Ronald [Penguin 1951], p.146
A Reaction
This strikes me as one of the most basic tenets of empiricism. It denies the existence of 'pure' reason, and instead asserts that it is built out of complex and abstracted sense experience, which makes it ultimately a second-class citizen.