Every cloud has a silver lining
Every bad situation has some good aspect to it. This proverb is usually said as an encouragement to a person who is overcome by some difficulty and is unable to see any positive way forward.
John Milton coined the phrase 'silver lining' in Comus: A Mask Presented at Ludlow Castle, 1634
I see ye visibly, and now believe
That he, the Supreme Good, to whom all things ill
Are but as slavish officers of vengeance,
Would send a glistering guardian, if need were
To keep my life and honour unassailed.
Was I deceived, or did a sable cloud
Turn forth her silver lining on the night?
I did not err; there does a sable cloud
Turn forth her silver lining on the night,
And casts a gleam over this tufted grove.
'Clouds' and 'silver linings' were referred to often in literature from then onward, usually citing Milton and frequently referring to them as Milton's clouds. It isn't until the days of the uplifting language of Victori's England that we begin to hear the proverbial form that we are now familiar with - 'every cloud has a silver lining'. The first occurrence that is unequivocally expressing that notion comes in The Dublin Magazine, Volume 1, 1840, in a review of the novel Marian; or, a Young Maid's Fortunes, by Mrs S. Hall, which was published in 1840:
As Katty Macane has it, "there's a silver lining to every cloud that sails about the heavens if we could only see it."
'There's a silver lining to every cloud' was the form that the proverb was usually expressed in the Victorian era. The currently used 'every cloud has a silver lining' did appear, in another literary review, in 1849. The New monthly belle assemblée, Volume 31 include what purported to be a quotation from Mrs Hall's book - "Every cloud has a silver lining", but which didn't in fact appear in Marian, which merely reproduced Milton's original text.