Here’s the practical advice nobody gave me before I started my PhD.

Twenty-five years ago, I packed my Jeep Wrangler and drove south for six hours to start a life-­defining journey: a doctoral program in the Harvard-MIT Division of Health Sciences and Technology. My old ride was filled in equal parts with books and apprehensions. Soon I would discover a campus where not even the sky was the limit, and where I’d learn the name for what I was feeling: impostor syndrome.

Today I mentor PhD students at Polytechnique Montréal. With them—and you—I share what I wish I had known when I first moved into Edgerton House. These are 12 things every PhD student should hear early, even if they often go without saying.

1. Understand what makes a PhD unique.

Yes, it involves classes, psets, and exams. But unlike other degrees, a PhD demands that you find and solve a problem no one has solved before. You’re expected to break the frontier of knowledge, write a lengthy dissertation about your work, and defend it before experts. If this sounds hard, trust your instincts.