Ambition is good. Ambition spurs people on to achieve more and more, to find new ways of doing things, to refine and perfect practices that have been in effect for a long time, or to blaze a new trail that nobody before had the vision to see. Daniel Plainview, the main character in Paul Thomas Anderson's astonishing There Will Be Blood, is a man with ambition. Played with a ferocious intensity by a towering Daniel Day-Lewis, Plainview embodies everything Americans like to think of as our best traits. He is hard-working, driven, and, because of his innovative thinking and salesmanship, a great success. Even with a baby to care for (christened H.W.), his thought processes always return first and foremost to how he can get precious crude oil out of the ground. This is a man who loves a challenge, so when he is visited one day by Paul (Paul Dano), a soft-spoken young man who claims to know about a piece of land with a wealth of oil underneath it, Daniel can't resist investigating the tip. Upon Daniel's arrival, he meets the rest of Paul's family, including Paul's twin brother, Eli (Dano again), who does not easily roll over for Daniel's seemingly generous cash offer for their land. This is the first of many confrontations between the cold-blooded capitalist and the floridly vocal faith healer, and these confrontations comprise the core of the plot. Spanning 30 years, the film observes the price paid by Plainview, and all the people around him, as his single-minded ambition mutates into misanthropy and fear, laying bare his soul as well as the soul of his chief antagonist. In the early sequences, Daniel Day-Lewis plays Plainview as a man who enjoys his talents, particularly the precise rhythm of the speech he gives to those whose land he wishes to purchase. He embodies the scariest aspect of great salesmen, the conviction that they are much smarter and savvier than the suckers who buy their wares. His voice has a gruff quality, but also a soothing purr in these sequences. He lulls his audience, both in the movie and in the theater, into believing that he knows exactly what he's doing and that every word he says can be trusted -- and that he's a reasonable man. As Eli, Paul Dano's voice vacillates between a soft-spoken gentleness in his serene moments and a thin, reedy growl during his Biblical orations. He goes toe-to-toe with Day-Lewis and provides the film with an air of mystery. His is in many ways a more difficult role, and it is a testament to this young actor's skill that he makes such a lasting impression on the audience as he plays his scenes against the unstoppable force of nature embodied by Day-Lewis. Paul Thomas Anderson uses all of the weapons at his disposal as a filmmaker to keep the audience engrossed and involved in Daniel Plainview's life. The cinematography by Robert Elswit captures the harsh landscape, and he shoots Day-Lewis in a way that emphasizes his angular face and frame -- his body is just as jagged as the rocks that he digs through. One of the film's many showpiece scenes involves an oil fire. Plainview looks on rapturously as the tremendous blaze burns one of his derricks, and Anderson, who is as talented a writer as he is a director, knows enough to let the scene play out in just the images. There is nothing Plainview could possibly say that could match the multitude of emotions he's experiencing, but the cinematography and the performance -- as well as Jonny Greenwood's unsettling music for the sequence -- get the point across with a formidable mastery. Dylan Tichenor's editing cuts to the point of every scene, but never once does the screenplay come right out and say with a fine point what it all means. Naturally, it is very hard not to read the film as an essay on the current political landscape -- an oilman and a fundamentalist religious leader using each other in order to get their way -- but if that's all this film were about then There Will Be Blood would date as quickly as Michael Moore's Fahrenheit 9/11. Like all of his other films, There Will Be Blood is at its core about a person's relationship with family, and how that affects everything that happens to them. Anderson deftly shows how living with ambition and greed eats away at Plainview over the course of decades. His relationship with H.W. grows more complicated, and an extended sequence with a man who claims to be his long-lost brother acts as a barometer for the character's emotional decline. These scenes echo a dinner at Eli's home, the only sequence in the film's 160-minute running time that Plainview isn't in, where the audience sees the true nature of the relationship between Eli and his father. Even for the film's shockingly brutal violence, the "blood" of the title refers primarily to family, to the inevitable fact that everyone has relationships that must be maintained, and must be cared for because if those relationships aren't nurtured, the results are always painful and occasionally tragic. All of Paul Thomas Anderson's films have been about family. Hard Eight is about a man creating a surrogate family out of the guilt he felt for messing up his original one; Boogie Nights is about a lost little boy attempting to find someone to nurture him; Magnolia is nothing else if not a cornucopia of stories about the need to make peace with parents; and Punch-Drunk Love is about the efforts of a man stunted by his domineering family to escape their influence. With grand themes about America and capitalism and religion and greed, There Will Be Blood might seem like an epic -- and it is -- but more importantly for Paul Thomas Anderson, this is his most personal film. Anderson's ambition as a filmmaker is the equal of his protagonist's ambition as an oilman; they both mine uncharted territories and reap great rewards from their efforts. This is the first film he has directed since becoming a father, and this might be the fact that gives viewers the key to understanding why this movie is such a landmark achievement. It might be a grand epic, but at its heart There Will Be Blood is the work of a formidably talented man reminding himself that his talent -- however outsized -- is not what should define him. Ambition is good, but our relationship with other people is more important. Anyone who forgets that, no matter how talented, is finished.