There are two ways to interpret this phrase that are in common use:
1. Someone who helps you when you are in need is a true friend.
2. Someone who needs your help becomes especially friendly to obtain it.
It seems that the majority understand and use it as version one. The earliest citation of the phrase also appears to interpret it that way.Origin
From Ennuis: 'Amicu certus in re incerta cernitur.'. Translated from the Latin as 'A sure friend is known when in difficulty.'.
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