Auguries of Innocence, a beautiful poem of William Blake, starts with the stanza:

To see a World in a Grain of Sand
And a Heaven in a Wild Flower
Hold Infinity in the palm of your hand
And Eternity in an hour

Which is exactly how I envisage the magic worldview of Jim Vaupel. He had the ability of «seeing the World in a Grain of Sand», with an excitement on what appeared often times to be small and simple ideas, but that he knew the potential and simply saw the big picture. That was what first fascinated me in his work and draw me in at a very early stage in my demographic career. As most students in demography, I read a lot of papers from Jim Vaupel while in my graduate studies at Cedeplar, Brazil. I recall how I marveled at a unique ability he had: combine mathematical depth and elegance with incredibly good—and also elegant—writing. This reflected, what I came to know later, his very own personality: cogent–but kind; strong-willed–but an ardent listener. He was a man of conviction and passion; motivated by his view and the pursuit of making it a reality through institutions and a solid legacy. He also excelled at making the right questions, the big questions, the pathbreaking questions. That made him not only a great philosopher and a true scientist, but also a visionary. He just knew when an approach had the potential to be further developed and make even more important breakthrough changes in the future. And that is also why providing answers was key and he knew when to make important tradeoffs between mathematical elegance and challenging demographic answers, as he closes a paper in 1986 regarding what he considered preliminary answers with: «they are thus not general or elegant, but they are answers».

In a very unusually sunny week in Odense in 2019, I met Jim Vaupel in person for the first time. I remember standing at the door, star-struck and nervous. He had recently had a hip replacement surgery and had more energy than I did! I will never forget this day. We spent the whole afternoon discussing ideas, making diagrams and writing down formulas by hand—pure old fashion writing just like I liked it! Few can understand the level of excitement Jim exuded once he got obsessed with an idea—it was deeply contagious. He listened to me attentively, and discussed it with me openly and vividly—his eyes even brighter, his cheeks even pinker. That was something incredible about him; he was so keen on discussing ideas that who or what you were was irrelevant. Once you were with him in the «ideas arena», he was just ready to fight—using powerful words and mathematical tools as his favorite weapons. But, most importantly, I felt seen and heard. And that was one of his powers: he had the ability to see that «grain of sand» in you, to believe more in your ideas than you yourself were able to believe them in the first place. In between walking to lunch in this very short visit of mine in Odense he told me: «I urge you to keep researching this». His motivating words and energy were just what I needed to keep myself going. And I know they will never leave me.

I will never forget when I presented in the seminar the next day and he opened the discussion session saying: «Well, you never know when you develop something and get to see someone working on it 30 years later!». My visit only lasted four days, but it was my «Eternity in an hour». I will forever be grateful for having had the opportunity to share this with him. I guess, all I wanted to say, is: thank you, Jim.