Full Idea
In the case of a wagon, we may only have correct belief, but someone who is able to explain what it is by going through its hundred parts has got hold of a rational account.
Clarification
'Rational account' translates 'logos'
Gist of Idea
A rational account of a wagon would mean knowledge of its hundred parts
Source
Plato (Theaetetus [c.364 BCE], 207b)
Book Reference
Plato: 'Theaetetus', ed/tr. Waterfield,Robin [Penguin 1987], p.125
A Reaction
A wonderful example. In science, you know smoking correlates with cancer, but you only know it when you know the mechanism, the causal structure. This may be a general truth.