A Three-legged chair

Things sometimes work in threes:

Three blind mice,

Three musketeers,

Three wise men.

Though there is no grace for a three-legged chair.

I am unbalanced, and when met with touch,

I am unkind.

I’m unstable,

Incapable of supporting myself, let alone anyone else.

I am a monstrosity amongst men,

A fault amongst furniture.

I am a three-legged chair.