人为某样东西实际支付的成本至少是标价的两倍，因为买来后设置、学习、维护、修理，以及最后处置，也需要耗费精力、时间和钱。不是所有的实际成本都在价签上。实际成本是标价的2倍。
With freedom, books, flowers and the moon who could not be happy?
When playing Monopoly， spend all you have to buy， barter， or trade for the Orange properties. Don’t bother with Utilities.
It is only through enforced standardization of methods, enforced adoption of the best implements and working conditions, and enforced cooperation that this faster work can be assured.
I do not believe in God… to the extent that theists have made their concept intelligible， they have given us no reason to think anything answers to it.
The real reward in science is knowing that your work can save lives.
心灵需要书本，就像一把剑需要磨刀石。