Thank you for such a complete account of the history of zero. Considering 0 as a number in its own right is proof that we have learned something a little deeper that goes a little beyond simple counting. Small children play at saying that they know a number smaller than 1, and they tell you “zero”, but in their tender childhood it seems that they have not yet understood this abstract fact by which zero, and after them, negative numbers must be considered numbers on an equal footing.