As per the title, what is the relationship between life (*zoe*) and light (*phos*) in John 1:4b?

Are we to understand *zoe* and *phos* as being related to *egeneto/gegonen* in v3 

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> eg. That life was [the creation/metaphorically speaking 'the dawn'] of all humanity,
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Or is it to be understood in relation to v5?

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> Eg. That life was [the light of salvation] of all mankind
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Or have I completely missed the point here?