Success and failure

Today I was asked a problem which was both obvious and interesting - namely 'when will you know whether your project is a success or a failure?'

It is obvious (the question, not the answer), because I have clearly set this up as a challenge. It is interesting because there are 2 distinct and possible contradictory levels of failure. at a challenge level I will fail as soon as my outgoings exceed £100 but can easily go on to succeed as a business. It would, of course be extremely foolish to allow a business to fail by deliberately starving it of investment, on the other hand it is a common failing of business people that they continue to throw money in in the belief that 'everything will turn out ok'.

So, to give as honest an answer as possible, this stage of my journey will end when I can see a revenue stream (It isn't currently my plan to incur extra overheads or to grow the business in terms of people or resource). At a challenge level I have a figure in my head to which I will invest, so that the challenge can fail without stopping the business.

Unless of course it's a sure chance..