A while ago I had an interesting discussion with a subscriber.

He asked a question that at first sounded easy, but the more I thought about it, the more I realised it was very difficult to answer. I could have come up with an answer immediately but I chose not to, to give me more time to think, but more importantly to give him a better answer.

As I researched the question I found that it was an issue that every great investor I looked at struggled with, at some time in his career.

An this, irrespective of how successful he has been over the long term.

The question was?