The symbol of pure science throughout the novel, Max Gottlieb stands out as Martin's greatest mentor in the novel, and yet, Gottlieb remains one of the saddest as well. Gottlieb is a German Jew, dedicated to the practice of research, a practice that he illustrates with the utmost patience, diligence, and belief. He is seen as an eccentric and is talked about in gossip rings everywhere he turns. He is, of course, German, and in the early twentieth century Americans believed that most "true scientific" research, at least that which was of great importance, came from Germany. Lewis makes Gottlieb German for this reason and also for the reason that it places him as an "outsider" of the utmost extreme, completely lacking a place in society. Gottlieb does not fit into the medical world because he believes in perfection and is angered by mediocrity and commercialism. Lewis adds to this the fact that he is not only European, but German in the middle of a wave of American anti-German sentiment from World War I. And, not only is he German but he is a Jew, always an "outsider," expelled from this place and that.
And thus, Gottlieb is the eccentric scientist with the cold heart except that he is not altogether cold, for he does love Martin in his own way, just as he loves his daughter, Miriam, and had come to depend on his wife. And yet, it is important to realize that there is a certain coldness in Gottlieb's aloneness. He is a lonely man who is destined to be unhappy. Life hands him miseries and though he has made important discoveries, he remains somewhat unappreciated. And, finally, he ends a senile old man. His genius is eradicated from him through a sad senility, and he is left with nothing except his daughter's undying care.
We may ask what it is that Lewis is trying to say by painting such a dim portrait. Perhaps he is saying that the scientist is doomed to failure, perhaps he is saying that extremes do not work and that Martin needs to find a balance. Perhaps he is simply romanticizing the self-sacrifice of the "truth seeker." Or, perhaps Lewis had to simply remove Gottlieb from the narrative so that Martin could be truly free. It seems that all these things are true.