a set of discursive events that form at the sime time groups of enunciations linked to each other by formal rules of deduction, and series of modifications in the enunciating subject, modifications that continually follow on from each other; and more precisely, in a demonstrative meditation, enunciations which are formally linked modify the subject as they develop, and liberate him from his convictions or induce systematic doubts, provoke illuminations or resolutions, free him from his attachments or his immediate certainties, induce new states, but inversely the decisions, fluctuations, displacements, primary or acquired qualifications of the subject make possible sets of new enunciations, which are regularly deduced from the others.