I read on Wikipedia that
Hume remarks that we may define the relation of cause and effect such that ``where, if the first object had not been, the second never had existed."
I do not understand this. Let's say A causes B. Then it does not necessarily mean A is the only cause of B. If C also causes B, it is possible that A has not happened but B has happened because C has happened AND "A causes B" is still a true sentence.
It seems more logical to say "if the second object (effect) did not exist the first object (cause) never had existed".