"At Yale, I initially continued research on the problems which I brought from Poland. Within a few months, I made five papers and then published them in the leading American and British magazines. They liked me, they came to the conclusion that Ptak is good and efficient. The head of the Department of Pathology was then Richard K. Gershon, would-be Nobel Prize winner, a Polish Jew in a third generation. He died of lung cancer in 1983, at the age of fifty. We were close friends; I spent the last months of his life with him. Sometimes, speaking with me, he joked: „You're too intelligent not to be Jewish."

“I don't like to stay long outside of Kraków. I was always happy to go back there, just like a cat. Well, that's my mental structure.”

“As for the number of people reluctant to me, I guess I fall in the national average. Maybe it's about talking openly what I think? For example, in 1980 an interview with several professors – including myself – was ran by the newspaper Dziennik Polski, very much against the then authorities. We've all been in favor of far-reaching changes, but each of us saw these changes differently. I am a nonbeliever. And there comes the „Solidarity” with holy masses and sprinkling corpses with holy water. I thought that policy of the University, beneficial to the „Solidarity”, was not always beneficial for the University itself. From time to time, friendly people try to affront me, even though I did not belong neither to the youth communist organization neither to the party, neither had I contacts with the communist Security Service. And generally I didn't have herd instincts.”

“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.”

“My professional work connects with intellectual play, with great passion. But I like to read, I'm interested in philosophy, religion and history. And I love dogs! Now I have two friends that take me out for a walk every day.”

“In my childhood, I had natural interests. I got a microscope from someone, I made a telescope myself – a very poor quality, but I could see the moon. First, I wanted to become an astronomer. I read books about astronomy by James Jeans. I even read Arthur S. Eddington, which I did not quite understand. On the other hand, Jan Dembowski's book Natural History of One Protozoan made a huge impression on me. I decided that I would go towards biology, that I would become a physician.”

“People spend unnecessarily high amounts of money on drugs or supplements that support immunity , meanwhile they do more harm to themselves by their way of life, for example by inadequate diet.”