The only ethical principle which has made science possible is that the truth shall be told all the time. If we do not penalize false statements made in error, we open up the way for false statements by intention. And a false statement of fact, made deliberately, is the most serious crime a scientist can commit.
[On marriage and permanent attachment:]Well, well -- the prizes all go to the women who 'play their cards well' -- but if they can only be won in that way, I would rather lose the game ... [C]lever [women] bide their time -- make themselves indispensable first, and then [=play hard to get]. Clever -- but I can't do it.