<span>Some people felt immigration causes terrorism in the United States, and immigration should be limited.</span>
Any injury can harm a person's mental health, but not being able to play a sport, the thing you love so much will seriously affect someone's health.
All of the nouns used (hammer, chain, furnace, brain, anvil) are explaining mighty things that the tiger is being compared to. The poem is simply saying that they are smart, speedy, and strong.
I hope this helped! If you have further questions don't be afraid to ask!
~Travis
