"I argued with Professor Julian Aleksandrowicz, because he used some therapeutic activities that I did not like, such as the debatable use of suppressive drugs. Once, I criticized him for that in public. I was already appointed a professor, when I had a nice conversation with Professor Aleksandrowicz. I started – „Sir, as a scientist...”. He interrupted me – „There are three categories of people involved in science. Scientists, they are the ones who take the test tubes, they pour something into them. There are scholars, like you. And finally, sir, there are thinkers.” Someone later pointed out that I did not answer him – „You are a thinker, sir.” Aleksandrowicz had something of a thinker in himself."
January 1, 1970
https://en.wikiquote.org/wiki/W%C5%82odzimierz_Ptak