Shakespearian sonnets have a particular structure where each line of the poem contains ten syllables (due to the use of iambic pentameter). This is, one might think, because ten sounds 'complete' to some extent, like 4. For example
Love alters not with his brief hours and weeks
Which alters when its alteration finds
Is there any explanation in number theory to why the number 10 might seem complete to human minds and ears?
Or perhaps there is a mathematical explanation for why 10 is chosen for the number of syllables in the line?
Are there examples in nature where sets have a magnitude of 10 elements, or where the number 10 signifies some sort of totality, whether in a cycle or other abstract setting?