Meditations 10.38

Remember that this which pulls the strings is the thing which is hidden within: this is the power of persuasion, this is life, this, if one may so say, is man. In contemplating thyself never include the vessel which surrounds thee and these instruments which are attached about it. For they are like to an axe, differing only in this that they grow to the body. For indeed there is no more use in these parts without the cause which moves and checks them than in the weaver's shuttle, and the writer's pen and the driver's whip.

(podcast episode) (original Greek)