that which is not possible, or which cannot be done or effected. A proposition is said to be impossible, when it contains two ideas which mutually destroy each other, and which can neither be conceived nor united together. Thus it is impossible that a circle should be a square; because we conceive clearly that squareness and roundness destroy each other by the contrariety of their figure.

There are two kinds of impossibilities, **physical** and **moral**. Physical impossibility is that which is contrary to the law of nature.

A thing is morally impossible, when of its own nature it is possible, but yet is attended with such difficulties, as that, all things considered, it appears impossible. Thus it is morally impossible that all men should be virtuous; or that a man should throw the same number with three dice a hundred times successively.

A thing which is impossible in law, is the same with a thing impossible in nature; and if any thing in a bond or deed be impossible to be done, such deed, &c. is void. 21 Car. I.