Experts (oenologist, nose of perfumery, fakir, contortionist, imitator, etc.) develop a sensitivity, a body's empowered to be able to live professionally. Enter in this peculiar profession is often realized through transmission by a peer. Over time, tangible performance may be decline, threatening the existence of such professional experts. The question of the transmission of these specific knowledges intervenes in the course of these professionals, investigated by semi-structured interviews.