When I think of the mentors in my life who have most shaped my career, David Altschuler is at the top of the list.

I first met David when I was a medical student, and I spent my last year of my MD-PhD working in his lab at Massachusetts General Hospital. At the time, a new type of DNA sequencer (Solexa, soon to be acquired by Illumina) had just arrived at the Broad, and I raised my hand to be one of the people in his lab to get it up and running.

At the time, most of David's lab was working on genome-wide association studies (GWASs), but David believed that sequencing was the next horizon. This gave me the opportunity to work with him closely, and figure out how next-generation sequencing could impact human genetics.

For reasons that I will never understand, and can never repay, David kept track of me as I went from his lab to residency and fellowship. Once a month, I would go over to his house on weekends and talk with him about the interface of cloud computing, machine learning, and biomedical research.

In particular, I remember sitting in his backyard one afternoon. I asked him why he gave so much of his time, as I felt like I had so little to offer in return. He said, "When I look at my calendar every day, most of it is bureaucracy. A lot of meetings, often very confrontational or controversial. It's not fun. And then, there are these rare and treasured meetings, where I get to spend an hour with a young trainee, who just wants advice and needs somebody to talk things through with. This is the most rewarding part of my day. These are the meetings I look forward to when I look at my calendar each morning!"

In addition to being a great mentor, one of the things that I most admire about David is his unvarnished quest for the truth. He is willing to look convention in the face, and when it smells wrong, he digs into the data. If there's something that is operationally hard, but needs to get done, he's not afraid to roll up his sleeves and take it on. I've tried to emulate this a lot in my own scientific pursuits.

I cannot express how much I enjoyed speaking with him today on Theory and Practice!