The Horse and the 22nd Sense
You know, there are things in history that make one wonder whether the famous philosophers of ancient times weren't subject to those same little interruptions that molest more modern thinkers. Take Aristotle for instance; he got up to five senses, and stopped! We'll never know whether it was the dinner bell or a particularly good debate in the forum, that stopped him there but, since then, scientists reckon they've found a further 22 !
First, let's deal with that 'sixth' sense, to which science has given the rather unwieldy name of 'proprioception'.
If, while he was rushing to catch the debate, Aristotle had continued pondering the question of senses, he might well have wondered what physical mechanism was responsible for keeping him informed about the angle of his limbs during his hurried dash.
Each articulation the scientific word for joint is designed to operate through a certain angle only; over-articulation is limited by little stops on the bones and by series of check ligaments, but these bone stops can be worn away gradually by rigorous exercise (most particularly when young horses are subjected to high stress exercise by being brought into training too early) and check ligaments can be torn under conditions of tiredness or high physical stress.
