Black ice almost got me

Even though the shade temperature during my run was in the mid 40s and most of the Parkway path is dry, there is a big patch of water from melting snow that still covers the path. The low temperature last night was about 25 (F), and that patch of water had a layer of ice under the water. From a distance the ice looked like a big puddle of water. My mind was wandering off exploring the world and I wasn't paying attention, and I ran into the ice and almost went down. My foot slipped on the ice, but I was able to keep my balance long enough to hobble over the the edge and hold onto a wooden railing while I regained my balance. I then walked through the ice and resumed my running. The puddle was about ten feet across.