Be careful what you think After much thought, Rene Descartes had his eureka moment where he stated ""I think, therefore I am"". Feeling absolute euphoria over this revelation, he wanted to share it with someone. Finding no one in the street, he went into a bar and said to the first person he saw ""I think, therefore I am"". Not understanding, the man said, that's great, but would you like to date my sister? Looking at the man's sister, Descartes said with some disdain ""I think Not"", and immediβ¦