When we have plenty of anything with us, our real character surfaces.
To explain my point, when a child takes birth in a prosperous family, the level to which he or she can make use of this life of convenience, decides the inner substance; similarly a politician who has highest authority to take decisions would show his intellect and character by what he/she does with that power; again when all means of communication are available to us, our interest in communicating with people indicates the presence or absence of interest in conversing with them.
Another way of understanding this is by studying people who could achieve much more with certain limiting conditions. That would give a comparitive viewpoint to the possibilities of human spirit.
Its only when we are short of certain conditions that we feel like attributing the blame of our state to external factors. The moment these external limitations are gone, there emerges the individual with his strenghts and frailties of mind. An image which is no more veiled by limiting circumstances.
Thus if you have to test the potential of any person, give him all that is required to work comfortably. His work will then be his true signature.