Riddle us this. Who's the worst doctor ever?
Why, it's Dr. Lessing of course.
Lessing works at the concentration camp, selecting prisoners who are too sick for work to be executed instead of, you know, treating them. It's called the Hippocratic Oath, Lessing. Look it up.
Despite his position at the camp, Guido initially sees Lessing as a friend and someone who might help his family through the ordeal.
Let's jump back to the film's first half to find out why.
When we first meet Dr. Lessing, Guido serves him dinner and successfully answers a riddle posed by the doctor: "The bigger it is, the less you see it." The answer: obscurity. Guido poses his own riddle, and Lessing instantly becomes obsessed with solving it. So obsessed, in fact, that he refuses to eat the dinner Guido's just brought him.
Later, Dr. Lessing is called back to Germany on business. As Guido says his goodbyes, we understand that the two formed a bond over their riddling escapades:
LESSING: I truly enjoyed myself with you. You're the most ingenious…waiter I've ever come across.
GUIDO: Thank you. You're the customer with the most culture I've ever served.
LESSING: Thank you.
And that's the last we see of Dr. Lessing until Guido's taken for a check-up at the concentration camp. There, Lessing recognizes Guido and sets it up so Guido can serve at a dinner for the camp officials. Guido hopes that Lessing will honor their friendship and help him and his family escape the camp.
At the dinner, we realize that Dr. Lessing's riddle obsession is the real reason for him singling out Guido, who, let's remember, is a riddle genius.
LESSING: So. Pay attention. "Fat, fat, ugly, ugly, all yellow in reality. If you ask me what I am, I answer, 'Cheep, cheep, cheep.' Walking along I go, 'Poopoo.' Who am I? Tell me true." A duckling, right? Is it a duckling? It's not! […] Help me, Guido. For heaven's sake, help me. I can't even sleep.
Guido just stares at Lessing in disbelief because…yeah, that's pretty unbelievable. All of the suffering he's endured, and this guy has the nerve to suggest his suffering at the hands of a riddle is equally horrible.
Doctor, Doctor, Give Us the News
So, what are we to make of Lessing here? Aren't humans driven to help those who are suffering—for example, by providing relief aid during a crisis? Doctors even more so because, again, the Hippocratic Oath?
While there are several ways to dissect Lessing's character, we see him as a critique of people's tendencies toward self-absorption. Science has shown us that we're more likely to help people if we can relate to them. So the further a person is from us and our "in-group"—through geography or class or religion or race—the less likely we are to feel driven toward helping them (source).
Think of it like this: you may feel empathy if someone in your community was injured in a car accident, but you'd likely feel more empathy if it was a friend—and even more if it was a family member. In each case, your likelihood for helping that person grows the closer they are to you.
The Holocaust is an extreme example of this principle. Nazi propaganda defined Jewish people as less than human, even going so far as to classify them as vermin or a disease (source). In doing so, they diminished people's empathic response toward the Jewish plight by pushing them out of the in-group, i.e., the human race.
To Nazis, the Jewish people weren't even people.
Dr. Lessing shows us this human flaw in action and then magnifies it tenfold. For him, there's no one else who counts except… him. His own concerns are the end-all-be-all of his empathic response, and those concerns center on solving riddles.
In short, somebody needs a reality check and some theory of mind. Pronto.