Edward Gibbon

No one ever said learning was to be easy, but it's part of the process of evolving as a human being, and we all have to go through it. When I look back, I see that each difficult time brought an important lesson. And I prefer to look at it with gratitude because I wouldn't be who I am today if I haven't gone through it all.

Supplying fuel for a Mars expedition from the lunar surface is often suggested, but it's hard to make it pay off - Moon bases are expensive, and just buying more rockets to launch fuel from Earth is relatively cheap.

It is no wonder that bank capital is regulated. When borrowing and lending is profitable, it is tempting for banks to scale up their operations and to borrow and lend too much in relation to their capital, in effect reducing the effectiveness of the potential capital cushion.