A person who thinks why something happens.
Then comes the moment of magic. He moved a wooden ruler from one place to another and said:
A philosopher will think why this moved.
My first reaction was of intrigue. What does that mean? To think. I am pretty sure I didn't follow the train of thought personally since I was too young to focus on things for long, but I preserved the moment in memory somehow. And this moment keeps coming back to me every few years reminding how very insightful that demonstration of displaced ruler was. There are layers and layers to its understanding and, most importantly, you can clearly see that these are there to be pealed off.
Of course the definition is too restrictive considering all the fundamental questions philosophy attempts to answer but this was a beautifully insightful act, free from a very simplistic physical-processes viewpoint that was used for all other professions in that class.