Hope springs eternal in the human breast

It is in the nature of man to look forward to better times, despite set-back and disappointments.

The proverb is  a quotation from Pope‘s Essay on Man (1733).

Hope springs eternal in the human breast:
Man never is, but always to be, blest.
The soul, unesay and confin’d from home,
Rests and expatiates in a life to come.

The second line means that man never is blissfully happy, yet always thinks he is about to be. In the fourth line ‘expatiates’ means ‘wanders freely’.

See also:

• Every cloud has a silver lining
• Never say die
• While there is life there is hope