He spoke to a group of 104 on the topic "Iran: friend or foe" during which he tried "to help people understand what life in Iran was like from within".
Having made his third visit to the country three months ago, he wanted to dispel common perceptions of Iran as being a danger.
The media in the United States and Israel was largely to blame for the country's reputation, he believed.
While the regime itself was anti-western, the people were not, he said.
"They have a view of the world not unlike ourselves."
Based in Wellington, Prof Geering was still involved in academia as he often acted as the "interface" between universities and the public through open lectures.
His Otago Boys High School form mate and former pharmacology professor, Emeritus Prof Fred Fastier, was at the meeting.
He was keeping himself busy by writing books and making submissions to select committees.
He recalled five other pupils from their form who held university chairs, but both men concluded they were the only surviving ones.
"Every time we meet we think it must be for about the last time," Prof Fastier said.
