الرجل الذي لا يستطيع بين حين وآخر أن يتخيّل أحداثاً وأحوالاً للوجود مخالفةً لمبدأ العلّيّة كما يعرفه، لن يُثري علمه بإضافة فكرة جديدة أبداً.

“The man who cannot occasionally imagine events and conditions of existence that are contrary to the causal principle as he knows it will never enrich his science by the addition of a new idea.”Max Planck — The new science: 3 complete works: Where is science going? The universe in the light of modern physics; The philosophy of physics (1959)