Data is a reality. Data put together is knowledge. A bunch of related facts. None of this is truth however.
There's a body of knowledge for every subject you care to look into, you could gather, gather, gather, like a great computer and be called 'intelligent'
That just about covers it. Notice I haven't mentioned understanding, or knowing. They are spiritual matters related to truth.
Semantics I suppose, but refreshing myself on the definition of truth I came up with "conformity with fact."
I agree with the idea that a person can collect information/data and not understand it; simply repeating facts (the factual basis being understood by others, usually) doesn't mean someone understands those facts and how they fit within the landscape of truth.
My comment was more directed at the idea that data isn't needed. I would agree that at some point one has to move beyond the established data in order to break new ground; to move beyond the knowledge of others to internalize the information and make it your own. However, this still must conform to objective truth/reality...as much as possible.
The idea of cup being full is an example of how knowledge obfuscates, so I agree we all should periodically empty our proverbial cup...heck, the shape of the tea is determined by the cup, so why not take it a step further and find a new cup altogether from time to time. Still, at some point, once the new cup and tea have been established, we must drink or we're wasting all that delicious sencha! Or omiki, as the spiritual case may be. Point being, sure, as much as possible get rid of presumption; open ourselves up to new possibilities; but respect the objective efforts of the master tea-maker.
So, don't memorize dates and other data, much is superfluous to application of axioms, but they still apply to the verification process since the data still reflects reality. Much can be inferred...the truth triangulated from such "meaningless" data. And if whatever we hold to be true doesn't match with objective (or as objective as possible) data, then it casts a doubt that is very reasonable.
Of course none of this applies to our own personal truths...those things which we apply to our own path, which is entirely our own internal compass. Plato would suggest we leave the cave to find a greater truth, but I would say what works for an individual is for the individual to determine. The shadows are real too and: "enlightenment and delusion: who is to say..."