When the sky falls we shall catch larks. A way of stating to a person that his scheme or proposal is absurd or ridiculous.
French: “Si le ciel tombait, il y aurait bien des alouettes.” Latin: “Quid, si redio ad illes, qui alunt, quid si nunc coelum ruat?”
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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