Cat's know a sucker a mile away though

there was this stage I went through where stray cats started gathering outside my window and yeowling at night, and following me around the yard when I went outside... I was quite sure if it was the middle ages that I would have been burnt at the stake as a witch... anyway, I started de-worming them, de-fleaing them and feeding them... but I could not keep them, then it would just break my heart when I moved so I try not to collect stray cats anymore... once ina while a really sick cat will come up to me... I take it to the vet and ask them to do what is best