In contemplating thyself never include the vessel which surrounds thee, and these instruments which are attached about it. For they are like an ax, 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.

X, 38 - Meditations (c. 161–180 CE) - Book X