We believe that we have 5 senses, yet there is a 6th one.It is more mysterious, buried deep within us, and it is indispensable.It is proprioception, the perception of the position of our body in space. It seems evident to us that we are constantly aware of where our hands, our legs, our head are situated. Yet, this ability is much more complex than we think. If light, noise, flavors, smells and wind are external sensations captured by our sensory organs, proprioception is turned towards the interior of our body. It is also impossible to "extinguish" this 6th sense, unlike with our ears, nose, and mouth that we can plug or close. Let us embark on the discovery of this invisible sense, practically unconscious, and yet essential to our existence.