The best Quotations

The only people who should really sin are the people who can sin and grin.
- Ogden Nash

Do you know the writers of the following quotations?

Quotation A woman should say: ''Have I made him happy? Is he satisfied? Does he love me more than he loved me before? Is he likely to go to bed with another woman?'' If he does, then it's the wife's fault because she is not trying to make him happy. - writer
Quotation Calamity is virtue's opportunity. - writer
Quotation If we do not hang together, we will all hang separately. - writer
Quotation Heard melodies are sweet, but those unheard are sweeter. - writer
Quotation Wisdom lies neither in fixity nor in change, but in the dialectic between the two. - writer
Quotation The graveyards are full of indispensable men. - writer