The question of the status and the mode of functioning of technologies which participate in our cognitive activity (action, perception, reasoning) is inseparable from the question of the bodily inscription of these faculties. One can adopt the principle that a tool is fully appropriate when it functions as a component of the organs of our lived body. However, these technical entities can be differentiated along a scale according to the role played by their separability. The possibility of picking up and putting down a hammer, a pair of spectacles, an agenda is part of the meaning of these tools. When they are “in hand”, they become transparent for the subject and serve in the constitution of his lived experience. Put down, they can be transmitted, modified, received. According to the frequency of the transition picking up/putting down, the tool can be picked up while anticipating that it can just as quickly put down again (the mouse of a computer, cutlery at table, an agenda, …). At the other extreme, another sort of tool functions rather as a prosthetic device that is taken up with the prospect of remaining attached to the body for a long time (an artificial leg, spectacles, clothes, …). This differentiation of technologies along a continuum which depends on forms of use seems to us sufficient to distinguish extension and embodiment.