Hope springs eternal
Definition 1 of 1
Pro Tip 1/3Eternal Optimism
The phrase suggests a deep-rooted optimism within humans, always looking for a positive future. 
Despite the economic downturn, he invested in his education, a true case of hope springs eternal.
Pro Tip 2/3Persistence Context
Use when highlighting someone's continuous efforts or belief in success, regardless of failures. 
She auditioned for the tenth time, because hope springs eternal.
Pro Tip 3/3Not Literal
Hope doesn't literally 'spring', the phrase is a metaphor for the resilience of hope. 
Though he lost the match, his desire to win was undiminished; hope springs eternal.