Schopenhauer said the fundamental drive of living things is the will to live — the striving to persist, and to keep the species going.

Nietzsche read him closely as a young man and eventually decided the answer was too defensive. Organisms do not behave like things whose project is continuation. They expand, take risks, seek out difficulty, spend themselves on things that endanger survival rather than serving it. A creature that only wanted to persist would not do most of what creatures do.

His replacement is the will to power: the drive to grow, to extend capacity, to overcome resistance — including its own.

Power over what

The word does the doctrine more damage than any objection to it.

Macht in Nietzsche is not political control, and the clearest cases in his work have nothing to do with ruling anybody. The artist forcing a form out of resistant material. The thinker going after the problem that defeats him. The person mastering a discipline that does not come easily.

The common structure is overcoming, and the resistance being overcome is frequently internal. On his account, power exercised over other people is one expression among many and usually a weak one — the mark of someone who cannot find the resistance anywhere better.

Nor is it advice. Nietzsche is not recommending that you acquire a will to power, any more than a physiologist recommends having a metabolism. He is claiming it is what drives are, everywhere, already. What he does have views about is the relation you take up to your own.

What it is actually for

The doctrine earns its place as a method, and the method is what has survived into ordinary use even where the metaphysics has not.

On the Genealogy of Morality (1887) applies it to morality itself. The argument: the dominant European moral vocabulary — humility as good, strength as suspect — is not a discovery about what is right but a historical product. It was made by people who lacked the power to achieve the older aristocratic goods and who inverted the scale instead, turning their incapacity into a virtue and the strength they could not match into a sin.

Whether that story is historically true matters less than what it demonstrates, which is a move: take a value system that presents itself as obvious and ask whose position it serves. Not who invented it deliberately — nobody did — but what configuration of strength and weakness it fits.

That question is now everywhere. It is behind ideology critique, behind most sociology of knowledge, and behind any argument that begins "look at who benefits from believing this". It also cuts in every direction, including at Nietzsche, and the honest version of the method accepts that.

Where it overreaches

The late notebooks push further: the will to power as the innermost nature of all reality, with physical force itself a manifestation of it.

This is the version Heidegger built his reading on, and it is the version most contemporary scholarship backs away from. The notebooks were unpublished, they were assembled after his death by an editor with her own purposes, and the claim is unfalsifiable in a way the rest of his work is not — if everything is will to power, the term has stopped distinguishing anything.

The defensible doctrine is narrower and more useful: a claim about drives, and a method for reading values as expressions of them. Taken that way it does not need to be true of electrons to be worth having.

Where the framework ends up pointing, once the inherited valuations have been seen through, is nihilism — which Nietzsche treated as the condition to be survived rather than the conclusion to be drawn.