There was once a very smart horse. Anything that was shown it, it mastered easily.
That is until the day its teachers tried to teach it about analytic geometry. To there surprise, the horse simply could not understand rectangular coordinates at all. All the horse’s acquaintances and friends tried to help, but neither they nor the horse could figure out what was the matter, and the so the horse continued to be confused by the subject.
Finally, a mathematician was brought in to assist. He looked at the problem, and then shook his head. “Of course he can’t do it,” he replied. “Do you know you’re putting Descartes before the horse?”