"Capital Preservation" as defined by some of the Great Investors...

Jesse Livermore - legendary trader - once mentioned this great axiom:

"They say there are two sides to everything. But there is only one side to the stock market; and it is not the bull side or the bear side, but the right side. It took me longer to get that general principle fixed firmly in my mind than it did most of the more technical phases of the game of stock market speculation." 

This reminds me of Warren Buffett and Seth Klarman. 

Warren Buffett once said that "the first rule of investing is "Don't lose money," and the second rule is, "Never forget the first rule."

Seth Klarman too has his own version. He too believe that "avoiding loss should be the primary goal of every investor. This does not mean that investors should never incur the risk of any loss at all. Rather "don't lose money" means that over several years an investment portfolio should not be exposed to appreciable loss of principal. 

While no one wishes to incur losses, you couldn't prove it from an examination of the behavior of most investors and speculators. The speculative urge that lies within most of us is strong; the prospect of a free lunch can be compelling, especially when others have already seemingly partaken. It can be hard to concentrate on potential losses while others are greedily reaching for gains and your broker is on the phone offering shares in the latest "hot" initial public offering. Yet the avoidance of loss is the surest way to ensure a profitable outcome." - as seen on mootleyfool 

There is another great saying by Prof. Sanjay Baksh*. He says "Risk and return are negatively correlated. If you want to increase return, you must reduce risk of permanent loss of capital.

*Value Investment (Guru and) Professor in Behavioral Finance and Business Valuation in Management Development Institute. India 

Happy Investing !!!