As Michel Foucault wrote, Descartes' Metaphysical Meditations are not only a demonstrative text ("a set of system-forming proposals") but they also require their reader to perform a series of spiritual exercises ("to be affected by a set of exercise forming modifications"). This intervention will therefore propose to carry out the exercises proposed by the First and Second Meditations of Descartes: from doubt to the famous "cogito", it will be an opportunity to try to verify, both together and individually, that the truth exists, and that it is experienced.