The cat (I'd like to say our cat but he won't let me) went into the garden and saw a squirrel on the grass a few meters away. Immediately the cat went into "I'm a hunting tiger" stance (despite his weight problem). The squirrel looked at the cat and the cat looked at the squirrel. Here they are in other circumstances:
A few years ago the cat could get to the top of trees 12 meters high, and sway in about in the wind fearlessly. I was so surprised I took a photo (from the third floor):
Then he discovered a nice restaurant on the first floor of our building, a lady who feeds him till he bursts.
So the cat looked at the squirrel and the squirrel looked at the cat, then the squirrel zipped along the grass and up a tree followed by the small podgy tiger. Up the tree the squirrel went. The cat tried it too, but got only a couple of meters before giving up and falling to the ground, breathing heavily and sweating a lot (I imagine).
"So, what is this 'timeless and universal lesson taught by nature' then?"
Keep a check on your Body Mass Index if you want to eat squirrel sandwiches for lunch.