Sextus Empiricus Pyrrhoniae Hypotyposes 1.16.178

[178] They hand down also Two other Modes leading to suspension of judgement. ¹ Since every object of apprehension seems to be apprehended either through itself or through another object, by showing that nothing is apprehended either through itself or through another thing, they introduce doubt, as they suppose, about everything. That nothing is apprehended through itself is plain, they say, from the controversy which exists amongst the physicists ² regarding, I imagine, all things, both sensibles and intelligibles; which controversy admits of no settlement because we can neither employ a sensible nor an intelligible criterion, since every criterion we may adopt is controverted and therefore discredited.