When still a student I made acquaintance with Hans in 1970, soon after his appointment at the Institute of Cultural Anthropology of Leiden University. Then and there scientific staff members were automatically offered the luxury of an undergraduate assistant. I became Hans’s second assistant, because my predecessor had been dismissed because of his outspoken condescending attitude towards the scientific standards at Amsterdam University, Hans's Alma Mater. In his classes Hans emphasised the mutual comparison of cultures according to the Amsterdam tradition, yet in Leiden structuralism was en vogue and students were trained to search for coherence of practices within cultures.
For four years I was Hans's assistant and we met on an almost daily basis. After, when in line with the ‘Leiden’-methodology I wrote my PhD-thesis on a prehistoric society of six thousand years ago, Hans became my Doktor-Vater (Doctor's Father, an informal overseer of the process), and he and I had lengthy discussions about the pros and cons of the two approaches, of course without ever reaching a consensus. Yet notwithstanding our disagreements Hans kindly promoted and enabled publication of parts of my thesis in interna-tional Journals.
Meanwhile the nature of our interactions evolved into friendship through mutual visits in Wassenaar (where the Claessens lived) and Leiden (my home town); our wives participated, too. After my PhD defense I was offered a position outside Leiden in the realm of prehistory, but to my delight the well appreciated and many-faceted contacts with Hans and his family continued as before.
At the passing of Hans’ one of the things that I much regret is that we never wrote an article or a book together; although we did edit several volumes of articles. In hindsight this is understandable, because my work was geared towards prehistoric societies and the methodologies appropriate to this endeavour whereas Hans was interested in present-day societies and how to deal with these scientifically.
As time passed by, Hans and I –and our wives– grew older but after retirement the friendship and the social interactions between ‘Wassenaar’ and ‘Leiden’ continued as before. Good meals and pleasant conversations at their and our residences were the main ingredients for this. Then, due to the sudden death of my dear wife Riet early in 2022 an extremely dark period in my personal life set in; a period of mourning in which I avoided all contacts, also with Hans and his wife Iet. Therefore Hans's passing away came as another massive shock to me. I will miss him, my dear friend and esteemed scientific sparring partner.