The eagle lives in a place that cannot be easily reached by human beings, and the speaker is definitely aware of this. The poem imagines what the eagle's world is like, and by extension imagines a world without people. Still, the speaker can only describe the landscape using human or human-like attributes. Those darned "people" just keep popping up in the poem, like when you're looking at some cool geological formation and can't help thinking, "Hey, that looks just like my Aunt Gertrude!" "The Eagle" is a classic case of a nature poem that ends up being just as much about the person describing the scenery as anything else.
The poem compares the natural world to a person who experiences all stages of life at once: infancy, adulthood, and old age.
The speaker is incapable of imagining a non-human world. The poem's humanistic descriptions of nature are symptomatic of a society that views nature only as a means to achieve other things, not as an end in itself.
The eagle remains motionless for most of the poem; if you're like us, though, you imagine him turning his head from time to time to look around. You know the eagle has tremendous strength for its size, and Tennyson knows that you know this. We've all seen eagles or comparable birds in action. The poem builds suspense by playing on the expectation that the eagle will perform some amazing feat of acrobatics or descend on some poor rabbit or fish…any moment now. But instead, the eagle takes a swan dive off the cliff and allows himself to "fall" far below. The eagle of course achieves this with almost effortless grace. Great vision, powers of flight, and big talons: the eagle must have been first in line when the eagle was assigning skills to all the animals.
The poem shows how exceptionally strong individuals often look awkward and bizarre to more ordinary individuals.
The eagle's strength manifests itself at the end of the poem as pure energy. To borrow an expression from physics, the poem converts the eagle's potential energy to kinetic energy.
"The Eagle" was inspired by Alfred Tennyson's explorations through the Pyrenees region of southern France, which began in his early twenties. But the poem features another kind of exploration: it allows us to see the world from the eagle's perspective. The high cliff and the sky are depicted as part of another world, one that is nearer to the heavens than to earth. The eagle has no competition in his domain: he flies around like he owns the place.
The speaker projects his own tendencies toward exploration onto the eagle. In fact, the eagle isn't really much of an explorer, but the speaker wants to think that his own travels imbue him with some of the eagle's grandeur and nobility.
Men? There are no human beings in the poem, so what's this about "men"? Well, the first word of the poem is "he," so we know that this eagle is a guy. But, really, how does the speaker know this? Clearly the speaker has chosen to assign a gender to the bird, and he must have had a reason for doing so. The eagle represents a kind of masculine ideal of power, solitude, and gracefulness. Just as a superhero seems most powerful when he holds his powers in reserve, the eagle awes us simply by standing there. He lives apart from society but can descend to our level when he needs to. You could easily read the eagle as an old-fashioned portrayal of a great and noble man. Nowadays, most of us wouldn't bat an eye if the eagle were called a "she."
The eagle is a fantasy of male power held in reserve. The eagle is located at the center of the sky, and he assumes a dominant position relative to the old-looking, "wrinkled" sea, which "crawls" before him as if in supplication.
The poem has nothing to do with gender. The speaker gives the eagle a male gender simply because it would have been customary to do so.