Diogenes Laertius Vitae philosophorum 10.1.31

[31] They reject dialectic as superfluous; holding that in their inquiries the physicists should be content to employ the ordinary terms for things. ¹ Now in The Canon Epicurus affirms that our sensations and preconceptions and our feelings are the standards of truth; the Epicureans generally make perceptions of mental presentations ² to be also standards. His own statements are also to be found in the Summary addressed to Herodotus and in the Sovran Maxims. Every sensation, he says, is devoid of reason and incapable of memory; for neither is it self-caused nor, regarded as having an external cause, can it add anything thereto or take anything therefrom. Nor is there anything which can refute sensations or convict them of error: