We are not quite sure of any one thing in biology; our knowledge of geology
is relatively very slight, and the economic laws of society are
uncertain to every one except some individual who attempts to set them
forth; but before the world was fashioned the square on the hypotenuse
was equal to the sum of the squares on the other two sides of a right
triangle, and it will be so after this world is dead; and the inhabitant
of Mars, if he exists, probably knows its truth as we know it.