Both in England and America when one permits a swing to come to rest one “lets the old cat die,” yet no one knows positively why this saying is used.
It seems to be so old that the original allusion is lost. In our opinion, however, it comes from the same source as the other common saying, “room to swing a cat.”
We may find it hard to realize now, but the time was not very remote when no one was at all concerned over the sufferings of dumb animals.
Thus, as Shakespeare reports in Much Ado about Nothing, there was an ancient archery sport in which a cat was put into a sack (a leather bottle, according to Shakespeare) which, in turn, was suspended from a tree; the efforts of the cat to escape provided a swinging target.
Probably it was no part of the sport to kill the cat, but it is more than likely that the poor beast was at least injured before the marksmen wearied of the sport.
So, we think, rather than to open the bag and run the risk of getting severely scratched by the injured animal, both bag and cat were left swinging from the tree until “the old cat died.”