Around September 1927, the philosopher Ray Monk argued that the physical world had changed. Indeed, for hundreds of years nature could be clearly separated from the human beings who studied it, and its parts had a location, an identity, obeyed the same laws, and behaved predictably. In the first quarter of the 20th century, the quantum caused some physicists to question these assumptions. The emergence of the uncertainty principle, published by Heisenberg was discussed by N. Bohr and opened a debate that would last a lifetime between Bohr and Einstein. Between these two scientists, a hypothesis is advanced: between the Newtonian world and the quantum world, no connections can be found. This was an obvious proof that nature was a much stranger place than thought, and the phrase with deep philosophical repercussions, which we propose to analyze, comes down not to the question of „what do I not know?”, but rather to „what can I not know?”