Can you answer this question please?

Why does the speaker repeat the words: 'the world thinks', 'I think' and 'tis thought'?

Shylock, the world thinks, and I think so too,

That thou but lead'st this fashion of thy malice

To the last hour of act; and then 'tis thought

Thou'lt show thy mercy and remorse more strange

Than is thy strange apparent cruelty;