The mathematician, biologist and physicist are seated in a street cafe watching people going in and coming out of the house on the other side of the street.
First they see two people entering the house.
Time passes.
After a while they notice three persons exiting.
The physicist remarks,
"The measurement wasn't accurate."
The biologist concludes,
"They have reproduced."
The mathematician says,
"Now if another person enters the house, it'll be empty again ..."
----------------A Final Thought ...
"Mathematics may be defined as the subject in which we never know what we are talking about, nor whether what we are saying is true."
- Bertrand Russell (1872–1970), British philosopher, mathematician