some mice have a wheel in the middle. generally what is this wheel for
Scroll wheel It is used, as the name suggests, for scrolling. It can often also be used as a third mouse button by pressing on it. The wheel is often – but not always – engineered with detents to turn in discrete steps, rather than continuously as an analog axis, to allow the operator to more easily intuit how far they are scrolling.
The Lion and the Mouse In the oldest versions, a lion threatens a mouse that wakes him from sleep. The mouse begs forgiveness and makes the point that such unworthy prey would bring the lion no honour. The lion then agrees and sets the mouse free. Later, the lion is netted by hunters. Hearing it roaring, the mouse remembers its clemency and frees it by gnawing through the ropes. The moral of the story is that mercy brings its reward and that there is no being so small that it cannot help a greater. Later English versions reinforce this by having the mouse promise to return the lion's favor, to its sceptical amusement.