Huc accedit ut in summa res nulla sit una,
unica quae gignatur et unica solaque crescat,
quin aliquoiu' siet saecli permultaque eodem
sint genere.
So it follows that in the whole [of everything] no single thing would exist
that all alone would be born and all alone would thrive
but-instead each-thing would be of-some-kind and very many
would belong to each kind. [of each kind there would be many instances]
Questions:
1. help me with the verb "siet". What is its dictionary headword?
2. does "aliquoiu'" = "aliquoius" = "alicuius"?
3. I am guessing about the passage that starts "quin...". Please parse this for me.