Is being an entrepreneur a medical condition? Mark Constantine, co-founder of Lush, the cosmetics empire, seems to think so. I met him while chairing a panel of retail entrepreneurs at a conference last week, and have wondered about his semi-serious remark to that effect since. Is the urge to start and run companies really a pathological affliction?

Unquestionably if you catch the bug it is incurable. Once someone has enjoyed the soaring highs of creating a new venture (and despite the inevitable lows), they can never revert to working for others. For them, life would be too boring.

Among entrepreneurs I know, the hunger to experiment and go for it cannot be satisfied except temporarily – restlessness enters the soul, a longing to seize opportunities and improve the order of things.