I got a little bit of tuna (because if it were starving, I feared a bigger portion might do more harm than good) and a small dish of water, then went outside. But the cat was gone. After a little searching, I found it in its old sideyard. As I approached it cowered and stared wildly, but didn't run. I placed the dishes at the foot of the wooden fence about 15 feet away, and then stepped back. By the time I had returned to the sidewalk it was by the dishes; but wouldn't eat until I disappeared. When I returned a few moments later, its head was dipping into a dish, and another cat, a robust, healthy one, was sitting behind it, watching me, almost as if keeping guard. I wouldn't expect so much empathy from a cat, but it makes a more moving story to see it that way.
Still later I returned to collect the dishes. The sickly tabby was still nearby. The tuna was gone, but there was still lots of water. When I gathered them up, the cat let out such a pitiful, desperate mew, that I was convinced to leave the water.