Character Analysis
A Life's Regret
One of the first things we learn about Strether in this book is that he tends to approach life with a lot of caution, even for a dude in 1903. We can see this when he first meets Maria Gostrey and feels nervous about going for a walk with her, as Maria almost instantly recognizes, "You're doing something that you think not right" (1.26). After all, Strether is engaged to a lady named Mrs. Newsome and Maria is more than 15 years younger than him. Welcome to Europe.
But for all that, we can tell that Strether's not totally satisfied with being Mr. Safe all the time. After all, that's why he overcomes his fear and goes for a walk with Maria—a decision that sets he first foundations for changing his life.
At first, Strether's response to this decision isn't a happy one. Instead, it fills him with regret about all the times he didn't make similar sorts of decisions when he was younger.
Strether has been to Europe before, in his younger years, and while walking with Maria he wonders to himself, "Had he come back after long years, in something already so like the evening of life, only to be exposed to it?" (3.15). Or in other words, rather than being happy with himself, he can only regret the fact that it has taken him up until old age before he could do something as simple as taking a walk with a stranger of the opposite sex.
Now you might think that Strether should focus more on the positive fact that at least he's now overcoming his fears. But for the entire first third of this book, Strether's only hope seems to come from the thought that other people still have a chance to enjoy their youth, even though it's too late for him.
Strether makes an especial point of banging this idea into the head of an artist named little Bilham, when he tells the young man: "Do what you like so long as you don't make my mistake. For it was a mistake. Live!" (5.2.14). Bilham tries to shrug off this speech, but Strether practically grabs him by the collar and pleads with the young man to live his youth to its fullest, for Strether's sake.
Now this is all pretty sad. But don't worry; there's still some hope for ol' Lewis Lambert Strether.
The Lamb
Strether has not only spent his life being cautious; he has also spent it serving other people. Strether, you see, has a complicated relationship to himself because he has never really taken the time to figure out what he actually wants out of the world. He has always let others people boss him around, especially his fiancée, Mrs. Newsome. When he first speaks to Maria Gostrey about Mrs. Newsome and her daughter, Sarah Pocock, Strether's only response can be, "I'm perhaps a little afraid of her" (2.1.33). And that's just the tip of the iceberg.
When Strether first runs across Chad, he's blown away by how much Chad has changed for the better since he escaped the influence of his mother and sister. Strether admits that there's a sense of safety that the Newsome have always given him, but he also realizes that it's the "general safety of being anchored by a strong chain" (2.1.191).
The paradox for Strether is that for most of his life, he has actually enjoyed this sense of safety. But now that he's getting on in years and out on his own, too, he's starting to regret all of the things he has missed out on because of his preference to play things safe.
In short, Strether barely knows who he is at fifty years old. But arriving alone in Europe makes him instantly realize that it's time to start figuring out what he wants. And this process eventually leads him to become…
His Own Man
The main plot of The Ambassadors is essentially the story of Strether's attempts to grow a backbone and to escape his role as Mrs. Newsome's personal ambassador. This is no easy feat, of course, since Strether has spent his entire life being super cautious. But the more he hangs around Maria Gostrey, Chad, and their Paris friends, the bolder he gets about disobeying Mrs. Newsome.
You can see this theme popping into existence from the very start: even his first moments in Europe get Strether to start thinking that "[What] he finally sat there turning over was the strange logic of his finding himself so free" (2.2.3). That's right, free! Mrs. Newsome has sent him on his trip to regain her control of Chad. But in reality, she risks losing another man.
You know that Strether has really made a break with Mrs. Newsome when he persuades Chad to stay in Paris instead of going home. Of course, he won't tell Mrs. Newsome about what he's doing; but even the choice to secretly disobey her was unthinkable to Strether back at the beginning of the novel.
Strether also has a tendency at the start of this novel to do whatever Waymarsh, his buzzkill of a friend from the States, tells him. Waymarsh is a total stick-in-the-mud, and Strether falls into the dangerous trap of constantly trying to cheer this miserable dude up. Ultimately, though, Strether is able to stand up to Waymarsh once he "know[s] what [he's] about" (10.2.29). In this same line, Strether insults Waymarsh by implying that his friend doesn't know how to enjoy life.
It's this "knowing what he's about" that allows Strether to finally start living for himself and not for others. And that's what makes him the hero.
Strether's Timeline