The last sentence is fitted with this parallel in Portia's speech:


"Consider this
That in the course of Justice none of us
Should see salvation."


Here, at least, Protestant theology, not Seneca, inspires Portia's
eloquence.

Now take Portia:


"The quality of Mercy is not strain'd;
It droppeth as the gentle rain from heaven
Upon the place beneath: it is twice blessed;
It blesseth him that gives and him that takes;"


(Not much Seneca, so far!)


"'Tis mightiest in the mightiest; it becomes
The throned monarch better than his crown;
His sceptre shows the force of temporal power,
The attribute to awe and majesty,
Wherein doth sit the dread and fear of kings;
But Mercy is above this sceptred sway,