hope

hope one of the three theological virtues.
hope deferred makes the heart sick proverbial saying, late 14 century, originally with biblical allusion; the implication is that it is worse to have had one's hopes raised and then dashed, than to have been resigned to not having something.
hope for the best and prepare for the worst proverbial saying, mid 16th century, recommending a balance between optimism and realism.
hope is a good breakfast but a bad supper while it is pleasant to begin something in a hopeful mood, the hopes need to have been fulfilled by the time it ends. The saying is recorded from the mid 17th century.
hope springs eternal a view that human nature is instinctively optimistic; this proverbial saying of the mid 18th century derives from Alexander Pope's Essay on Man (1733), ‘Hope springs eternal in the human breast: Man never Is, but always To be blest.’
if it were not for hope, the heart would break hope wards of complete despair; proverbial saying, mid 13th century.

See also abandon hope, while there's life there's hope, he that lives in hope.