The Will to Power is Nietzsche's best attempt to describe the eternal recurrence, as it is basically a book of notes that were intended to evolve into his magnum opus.
He never got to finish it. The first volume, The Antichrist, was finished and published before it was too late, but he planned to write many more books in a series, with the final volume entitled The Eternal Recurrence.
Much of the book includes letters written in an attempt to explain his thoughts to others. This makes it a treasured read for any Nietzsche fan, or anyone interested in the philosophy behind living in a nihilistic Universe where the only drive to do anything is the possibility that you can never experience anything other than what you set yourself up to experience, without ever NOT experiencing life. The overman is confident in the fact that he will live his life over and over again, and sees every great moment for what it is -- an experience, not just a distant memory. Here are some of the finer sections from The Will to Power, translated by Walter Kaufmann.
1063 (1886-1887) -- The law of the conservation of energy demands eternal recurrence.
1061 (1887-1888) -- The two most extreme modes of thought--the mechanistic and the Platonic--are reconciled in the eternal recurrence: both as ideals.
1064 (1885) -- That a state of equilibrium is never reached proves that it is not possible. But in an indefinite space it would have to have been reached. Likewise in a spherical space. The shape of space must be the cause of eternal movement, and ultimately all "imperfection." That "force" and "rest," "remaining the same," contradict one another. The measure of force (as magnitude) as fixed, but its essense is flux. "Timelessness" to be rejected. At any precise moment of a force, the absolute conditionality of a new distribution of all its forces is given: it cannot stand still. "Change" belongs to the essense, therefore also temporarily: with this, however, the necessity of change has only been posited once more conceptually.
1067 (1885) --
And do you know what "the world" is to me? Shall I show
it to you in my mirror? This world: a monster of energy,
without beginning, nor end; a firm, iron magnitude of force
that does not grow bigger or smaller, that does not expend
itself but only transforms itself; as a whole, of unalterable
size, a household without expenses or losses, but likewise
without increase or income; enclosed by "nothingness" as by a
boundary; not something blurry or wasted, not something
endlessly extended, but set in a definite space as a definite
force, and not a space that might be "empty" here or there,
but rather as force throughout, as a play of forces and waves
of forces, at the same time one and many, increasing here and
at the same time decreasing there; a sea of forces flowing and
rushing together, eternally changing, eternally flooding back,
with tremendous years of recurrence, with an ebb and a flood
of its forms; out of the simplest forms striving toward the
most complex, out of the stillest, most rigid, coldest forms
toward the hottest, most turbulent, most self-contradictory,
and then again returning home to the simple out of this
abundance, out of the play of contradictions back to the joy
of concord, still affirming itself in this uniformity of its
courses and its years, blessing itself as that which must
return eternally, as a becoming that knows no satiety, no
disgust, no weariness: this, my Dionysian world of the
eternally self-creating, the eternally self destroying, this
mystery world of the twofold voluptous delight, my "beyond
good and evil," without goal, unless the joy of the circle is
itself a goal; without will, unless a ring feels good will
toward itself--do you want a name for this world? A solution
for all of its riddles? A light for you too, best-concealed,
strongest, most intrepid, most midnightly men?--This world is
the will to power, and nothing besides! And you yourselves
are also this will to power--and nothing besides!