Chance

I've just finished reading 'Nietzsche, Genealogy, History', and came across
a curious sentence that I was hoping that perhaps someone could explicate.
It's on p.89 of the Foucault Reader, and is related to the concept of
chance. Having just quoted Nietzsche as saying that there is only 'the iron
hand of necessity shaking the dice-box of chance,' Foucault goes on to say:

'Chance is not simply the drawing of lots, but raising the stakes in every
attempt to master chance through the will to power, and giving rise to the
risk of an even greater chance.'

Now, I must admit that my knowledge of Nietzsche is a bit sketchy, and this
may in fact be very simple - but would someone please explain to me what
this theory of chance that Foucault is using is?

Thanks in advance,

Jamie

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