What is the poem "The Eagle" by Lord Alfred Tennyson about?

This little gem of a poem packs quite a vivid description
of an eagle into a mere 6 lines!  The poem describes a lone eagle as it perches on a
stoney outcrop above water below.  In the last line of the poem, the eagle takes flight
and soars down to possibly catch some prey.  The poem is filled with alliteration in the
first line with all of the harsh "c" sounds:  He clasps the crag of crooked hands."  His
isolation is emphasized by the alliteration in line 2 "lonely lands."  There is a
wonderful description of how the water would look from above when it is described as a
"wrinkled sea" that "crawls."  The last line of the poem plays off of an allusion to the
might Zeus whose symbol/weapon is the lightning bolt.  The line says that the eagle
falls like a lightning bolt suggesting speed and power as he launches off his mountain
wall down towards to the water below.