Riverdale Park

Half a mile from my house is an undeveloped park on the Hudson River.  It is wooded and runs along the MetroNorth tracks between Spuyten Duyvil and Riverdale stations.  Almost every morning my dog Prophet and I walk several miles on (and off!) the trails.
In winter, with the leaves off the trees, every step presents views of the river and the Palisades on the other side.  This morning we saw an osprey sit on the winds coming off the Hudson, then drop into a lower altitude, and drop again, and drop again, until it was ready to roost on a limb of a dead tree.
When the sun came up today, about quarter after seven, the sky was a bright red on this side of the ridge, facing University Avenue.  Over in the park, the sun really never came out.  It was overcast and both the river and the Palisades were kind of gray.
Prophet likes off-trail adventures.  I don't know whether this is his own disposition or something he picked up from me, but I do know that he pushes me to join him even on days when I am feeling a little under the weather, like today.  We had to scramble down a steep frozen slope to a retaining wall near the tracks.  We had to drop down to a little marsh where a creek meanders through winter-dry cattails before dropping into a pipe and under the MetroNorth right of way.  We had to cross that same creek higher up on the icy trunk of a tree that toppled across.
Here is a good place to stop and interrogate my use of the phrase "had to."  Prophet is good at expressing his route preferences.  But he is really cooperative about going the way I want to.  So had I -- for example -- simply walked by that improvised bridge, Prophet would have, too… with a smile.  Instead, I encouraged  him and then followed.  I am writing this, so there is no suspense:  I made it across without slipping off and cracking my brain on the rocks below.  But as I crossed, I didn't know that, and I kept asking myself, "Why am I doing this?"
I have no answer.  Since the summer I have been taking blood thinners for CAD.  Small falls mean big bruises and sometimes bleeding that just won't stop.  And I am highly conscious of this when Prophet and I are scrambling down these steep slopes.  He loves to stand right in my path, staring at my feet, waiting for me to dislodge a rock or a clod of dirt that he can avidly pursue down the hillside.  It only heightens my awareness of the possibility that I could just as easily dislodge myself.
But crossing the stream on that log is a whole other order of danger.  When Prophet was little and heedless I had to forego it altogether because he thought nothing of slamming into my calves and taking me off my feet.  Now we can cross when it is dry.  But rain and ice make me acutely conscious of the rocks eight feet below.  It is a long enough fall to do some damage.  And yet…