244 An Essay on the Signs of Ideas. 
organ. ‘The feeling of fatigue is peculiar to 
the muscles. In the bones we have the sen- 
sation of aching; the sensation of griping 
is confined to the bowels. Heat and cold 
and the sensations produced by resisting sur- 
faces, as hardness, softness, roughness, smooth- 
ness, figure, are almost peculiar to the skin, 
the internal parts being much less susceptible 
of them. Titillation and itching occur in the 
skin; lancinating pain is peculiar to serous 
membranes, as the pleura, and peritoneum. — 
Tendons and ligaments are nearly insensible of 
cutting, burning, or pinching, but when twis- 
ted, or stretched, they evince an acute sensi- 
bility. 
Now, with regard to the feelings which I 
have just enumerated, as occurring, on certain 
occasions, in various organs or textures of the 
human system, it is almost unnecessary to 
state, that, some of them are capable of re- 
turning when the agents which originally ex- 
cited them are removed, whilst others are in- 
capable of returning without a fresh applica- 
tion of the original cause. 
When the sensations of any organ or tex- 
ture are experienced whilst the objects or 
agents from which they first arose are absent, 
those feelings so experienced, are called Ideas, 
or Remembered sensations. 
