How to interpret this comma?

Question

ですから、一回限りの人生、かけがえのない自己を大切にしようではありませんか。

So, shall we value this irreplaceable self in this life that we have but once? (example sentence from A Dictionary of Intermediate Japanese Grammar)

How did the translator make the bolded connection (に、には)? Can 読点 work here to list [predicate]人生 and [predicate]自己? That is, "shall we value this one life that we have but once and ourselves, who are irreplaceable?

What is the grammar behind this? Assuming this structure can't mean "and", how would you best rephrase it so that it does?

Answer 1

In this sentence, I think the author suggests valuing one important thing, life. Not two things (life and self) separately.

So I would say this 読点 (comma) servers as an appositive marker. That is to say, 一回限りの人生 and かけがえのない自己 are the same idea described in two different ways.

To translate this literally, you can use comma as well in English:

Let's value the life that is unrepeatable, the self that is irreplaceable.

The example translation in your textbook looks like a free translation, but at least they are treating them as one concept.

Answer 2

You can interpret it as …人生 and …自己 as you suggest, but it's more like a noun used like an adverb like 一生（いっしょう）i.e. "during your life".

…に or には don't make sense along with the predicate 大切にしよう. Though 人生に一度は大切にしよう means "let's take care of it at least once in your life". Basically に ≠ in.