Plato's English in "Laws"

I was reading a philosophical sentence in English, which was quoted on twitter by someone, but I could not understand it well.

Athenian Stranger: Much sleep is not required by nature, for our souls or our bodies, for no one who is asleep is good for anything.

My friend on Lang-8, Lynkusu taught me what the sentence meant like below:

The first part of the sentence means "People naturally do not require a large amount of sleep".

The second part means "Neither our bodies nor our souls require too much sleep".

The last part means "Because when we're asleep we're not good for anything".

So, the sentence rewritten is "Neither our bodies nor souls naturally require a large amount of sleep, because when we're asleep we're not good for anything."

This new sentence made sense for me. So I also rewrote it into "Much sleep is not required by nature. Much sleep is not required for our souls or our bodies. Because when we're asleep we're not good for anything."

Sometimes it's hard for me to grasp the meaning of "for".