Full Idea
Doubtful questions should not be discussed in terms of visible objects or in relation to them, but only with reference to ideas conceived by the intellect.
Gist of Idea
When questions are doubtful we should concentrate not on objects but on ideas of the intellect
Source
Plato (Parmenides [c.366 BCE], 135e)
Book Reference
Plato: 'Plato IV (Cratylus,Parmenides,Hippias Maj, Min)', ed/tr. Fowler,H.N. [Harvard Loeb 1926], p.231